Justice Powell
delivered the opinion of the Court.
The Pattern Makers’ League of North America, AFL-CIO (League), a labor union, provides in its constitution that resignations are not permitted during a strike or when a strike is imminent. The League fined 10 of its members who, in violation of this provision, resigned during a strike and returned to work. The National Labor Relations Board held that these fines were imposed in violation of § 8(b)(1)(A) of the National Labor Relations Act, 29 U. S. C. § 158(b)(1)(A). We granted a petition for a writ of certiorari in order to decide whether § 8(b)(1)(A) reasonably may be construed by the [97]*97Board as prohibiting a union from fining members who have tendered resignations invalid under the union constitution.
M
The League is a national union composed of local associations (locals). In May 1976, its constitution was amended to provide that
“[n]o resignation or withdrawal from an Association, or from the League, shall be accepted during a strike or lockout, or at a time when a strike or lockout appears imminent.”
This amendment, known as League Law 13, became effective in October 1976, after being ratified by the League’s locals. On May 6, 1977, when a collective-bargaining agreement expired, two locals began an economic strike against several manufacturing companies in Rockford, Illinois, and Beloit, Wisconsin. Forty-three of the two locals’ members participated. In early September 1977, after the locals formally rejected a contract offer, a striking union member submitted a letter of resignation to the Beloit Association.1 He returned to work the following day. During the next three months, 10 more union members resigned from the Rockford and Beloit locals and returned to work. On December 19, 1977, the strike ended when the parties signed a new collective-bargaining agreement. The locals notified 10 employees who had resigned that their resignations had been rejected as violative of League Law 13.2 The locals further informed the [98]*98employees that, as union members, they were subject to sanctions for returning to work. Each was fined approximately the equivalent of his earnings during the strike.
The Rockford-Beloit Pattern Jobbers’ Association (Association) had represented the employers throughout the collective-bargaining process. It filed charges with the Board against the League and its two locals, the petitioners. Relying on § 8(b)(1)(A), the Association claimed that levying fines against employees who had resigned was an unfair labor practice.3 Following a hearing, an Administrative Law Judge found that petitioners had violated § 8(b)(1)(A) by fining employees for returning to work after tendering resignations. Pattern Makers’ League of North America, 265 N. L. R. B. 1332, 1339 (1982) (decision of G. Wacknov, ALJ). The Board agreed that § 8(b)(1)(A) prohibited the union from imposing sanctions on the 10 employees.4 Pattern Makers’ [99]*99League of North America, supra. In holding that League Law 13 did not justify the imposition of fines on the members who attempted to resign, the Board relied on its earlier decision in Machinists Local 1327 (Dalmo Victor II), 263 N. L. R. B. 984 (1982), enf. denied, 725 F. 2d 1212 (CA9 1984).5
The United States Court of Appeals for the Seventh Circuit enforced the Board’s order. 724 F. 2d 57 (1983). The Court of Appeals stated that by restricting the union members’ freedom to resign, League Law 13 “frustrate^] the overriding policy of labor law that employees be free to choose whether to engage in concerted activities.” Id., at 60. Noting that the “mutual reliance” theory was given little weight in NLRB v. Textile Workers, 409 U. S. 213 (1972), the court rejected petitioners’ argument that their members, by participating in the strike vote, had “waived their Section 7 right to abandon the strike.” 724 F. 2d, at 60-61. Finally, the Court of Appeals reasoned that under Scofield [100]*100v. NLRB, 394 U. S. 423 (1969), labor organizations may impose disciplinary fines against members only if they are “free to leave the union and escape the rule[s].” 724 F. 2d, at 61.
We granted a petition for a writ of certiorari, 469 U. S. 814 (1984), to resolve the conflict between the Courts of Appeals over the validity of restrictions on union members’ right to resign.6 The Board has held that such restrictions are invalid and do not justify imposing sanctions on employees who have attempted to resign from the union. Because of the Board’s “special competence” in the field of labor relations, its interpretation of the Act is accorded substantial deference. NLRB v. Weingarten, Inc., 420 U. S. 251, 266 (1975). The question for decision today is thus narrowed to whether the Board’s construction of § 8(b)(1)(A) is reasonable. See NLRB v. City Disposal Systems, Inc., 465 U. S. 822, 830 (1984). We believe that § 8(b)(1)(A) properly may be construed as prohibiting the fining of employees who have tendered resignations ineffective under a restriction in the union constitution. We therefore affirm the judgment of the Court of Appeals enforcing the Board’s order.
K
A
Section 7 of the Act, 29 U. S. C. § 157, grants employees the right to “refrain from any or all [concerted] . . . activities . . . .”7 This general right is implemented by [101]*101§ 8(b)(1)(A). The latter section provides that a union commits an unfair labor practice if it “restraint] or coerce[s] employees in the exercise” of their § 7 rights.8 When employee members of a union refuse to support a strike (whether or not a rule prohibits returning to work during a strike), they are refraining from “concerted activity.” Therefore, imposing fines on these employees for returning to work “restraints]” the exercise of their §7 rights. Indeed, if the terms “refrain” and “restrain or coerce” are interpreted literally, fining employees to enforce compliance with any union rule or policy would violate the Act.
Despite this language from the Act, the Court in NLRB v. Allis-Chalmers Mfg. Co., 388 U. S. 175 (1967), held that § 8(b)(1)(A) does not prohibit labor organizations from fining current members. In NLRB v. Textile Workers, supra, and Machinists v. NLRB, 412 U. S. 84 (1973) (per curiam), the Court found as a corollary that unions may not fine former members who have resigned lawfully. Neither Textile Workers, supra, nor Machinists, supra, however, involved a provision like League Law 13, restricting the members’ right to resign.
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Justice Powell
delivered the opinion of the Court.
The Pattern Makers’ League of North America, AFL-CIO (League), a labor union, provides in its constitution that resignations are not permitted during a strike or when a strike is imminent. The League fined 10 of its members who, in violation of this provision, resigned during a strike and returned to work. The National Labor Relations Board held that these fines were imposed in violation of § 8(b)(1)(A) of the National Labor Relations Act, 29 U. S. C. § 158(b)(1)(A). We granted a petition for a writ of certiorari in order to decide whether § 8(b)(1)(A) reasonably may be construed by the [97]*97Board as prohibiting a union from fining members who have tendered resignations invalid under the union constitution.
M
The League is a national union composed of local associations (locals). In May 1976, its constitution was amended to provide that
“[n]o resignation or withdrawal from an Association, or from the League, shall be accepted during a strike or lockout, or at a time when a strike or lockout appears imminent.”
This amendment, known as League Law 13, became effective in October 1976, after being ratified by the League’s locals. On May 6, 1977, when a collective-bargaining agreement expired, two locals began an economic strike against several manufacturing companies in Rockford, Illinois, and Beloit, Wisconsin. Forty-three of the two locals’ members participated. In early September 1977, after the locals formally rejected a contract offer, a striking union member submitted a letter of resignation to the Beloit Association.1 He returned to work the following day. During the next three months, 10 more union members resigned from the Rockford and Beloit locals and returned to work. On December 19, 1977, the strike ended when the parties signed a new collective-bargaining agreement. The locals notified 10 employees who had resigned that their resignations had been rejected as violative of League Law 13.2 The locals further informed the [98]*98employees that, as union members, they were subject to sanctions for returning to work. Each was fined approximately the equivalent of his earnings during the strike.
The Rockford-Beloit Pattern Jobbers’ Association (Association) had represented the employers throughout the collective-bargaining process. It filed charges with the Board against the League and its two locals, the petitioners. Relying on § 8(b)(1)(A), the Association claimed that levying fines against employees who had resigned was an unfair labor practice.3 Following a hearing, an Administrative Law Judge found that petitioners had violated § 8(b)(1)(A) by fining employees for returning to work after tendering resignations. Pattern Makers’ League of North America, 265 N. L. R. B. 1332, 1339 (1982) (decision of G. Wacknov, ALJ). The Board agreed that § 8(b)(1)(A) prohibited the union from imposing sanctions on the 10 employees.4 Pattern Makers’ [99]*99League of North America, supra. In holding that League Law 13 did not justify the imposition of fines on the members who attempted to resign, the Board relied on its earlier decision in Machinists Local 1327 (Dalmo Victor II), 263 N. L. R. B. 984 (1982), enf. denied, 725 F. 2d 1212 (CA9 1984).5
The United States Court of Appeals for the Seventh Circuit enforced the Board’s order. 724 F. 2d 57 (1983). The Court of Appeals stated that by restricting the union members’ freedom to resign, League Law 13 “frustrate^] the overriding policy of labor law that employees be free to choose whether to engage in concerted activities.” Id., at 60. Noting that the “mutual reliance” theory was given little weight in NLRB v. Textile Workers, 409 U. S. 213 (1972), the court rejected petitioners’ argument that their members, by participating in the strike vote, had “waived their Section 7 right to abandon the strike.” 724 F. 2d, at 60-61. Finally, the Court of Appeals reasoned that under Scofield [100]*100v. NLRB, 394 U. S. 423 (1969), labor organizations may impose disciplinary fines against members only if they are “free to leave the union and escape the rule[s].” 724 F. 2d, at 61.
We granted a petition for a writ of certiorari, 469 U. S. 814 (1984), to resolve the conflict between the Courts of Appeals over the validity of restrictions on union members’ right to resign.6 The Board has held that such restrictions are invalid and do not justify imposing sanctions on employees who have attempted to resign from the union. Because of the Board’s “special competence” in the field of labor relations, its interpretation of the Act is accorded substantial deference. NLRB v. Weingarten, Inc., 420 U. S. 251, 266 (1975). The question for decision today is thus narrowed to whether the Board’s construction of § 8(b)(1)(A) is reasonable. See NLRB v. City Disposal Systems, Inc., 465 U. S. 822, 830 (1984). We believe that § 8(b)(1)(A) properly may be construed as prohibiting the fining of employees who have tendered resignations ineffective under a restriction in the union constitution. We therefore affirm the judgment of the Court of Appeals enforcing the Board’s order.
K
A
Section 7 of the Act, 29 U. S. C. § 157, grants employees the right to “refrain from any or all [concerted] . . . activities . . . .”7 This general right is implemented by [101]*101§ 8(b)(1)(A). The latter section provides that a union commits an unfair labor practice if it “restraint] or coerce[s] employees in the exercise” of their § 7 rights.8 When employee members of a union refuse to support a strike (whether or not a rule prohibits returning to work during a strike), they are refraining from “concerted activity.” Therefore, imposing fines on these employees for returning to work “restraints]” the exercise of their §7 rights. Indeed, if the terms “refrain” and “restrain or coerce” are interpreted literally, fining employees to enforce compliance with any union rule or policy would violate the Act.
Despite this language from the Act, the Court in NLRB v. Allis-Chalmers Mfg. Co., 388 U. S. 175 (1967), held that § 8(b)(1)(A) does not prohibit labor organizations from fining current members. In NLRB v. Textile Workers, supra, and Machinists v. NLRB, 412 U. S. 84 (1973) (per curiam), the Court found as a corollary that unions may not fine former members who have resigned lawfully. Neither Textile Workers, supra, nor Machinists, supra, however, involved a provision like League Law 13, restricting the members’ right to resign. We decide today whether a union is precluded from fining employees who have attempted to resign when resignations are prohibited by the union’s constitution.9
[102]*102B
The Court’s reasoning in Allis-Chalmers, supra, supports the Board’s conclusion that petitioners in this case violated § 8(b)(1)(A). In Allis-Chalmers, the Court held that imposing court-enforceable fines against current union members does not “restrain or coerce” the workers in the exercise of their §7 rights.10 In so concluding, the Court relied on the legislative history of the Taft-Hartley Act. It noted that the sponsor of § 8(b)(1)(A) never intended for that provision “ 'to interfere with the internal affairs or organization of unions,’” 388 U. S., at 187, quoting 93 Cong. Rec. 4272 (1947) (statement of Sen. Ball), and that other proponents of the measure likewise disclaimed an intent to interfere with unions’ “internal affairs.” 388 U. S., at 187-190. From the legislative history, the Court reasoned that Congress did not intend to prohibit unions from fining present members, as this was an internal matter. The Court has emphasized that the crux of Allis-Chalmers’ holding was the distinction between “internal and external enforcement of union rules . . . .” Scofield v. NLRB, 394 U. S., at 428. See also NLRB v. Boeing Co., 412 U. S. 67, 73 (1973).
The congressional purpose to preserve unions’ control over their own “internal affairs” does not suggest an intent to authorize restrictions on the right to resign. Traditionally, union members were free to resign and escape union discip[103]*103line.11 In 1947, union constitutional provisions restricting the right to resign were uncommon, if not unknown.12 Therefore, allowing unions to “extend an employee's membership obligation through restrictions on resignation” would “expan[d] the definition of internal action” beyond the contours envisioned by the Taft-Hartley Congress. International Assn. of Machinists, Local 1414 (Neufeld Porsche-Audi, Inc.), 270 N. L. R. B. No. 209, p. 11 (1984).13
C
Language and reasoning from other opinions of this Court confirm that the Board’s construction of § 8(b)(1)(A) is rea[104]*104sonable. In Scofield v. NLRB, supra, the Court upheld a union rule setting a ceiling on the daily wages that members working on an incentive basis could earn. The union members’ freedom to resign was critical to the Court’s decision that the union rule did not “restrain or coerce” the employees within the meaning of § 8(b)(1)(A). It stated that the rule was “reasonably enforced against union members who [were] free to leave the union and escape the rule.” Id., at 430. The Court deemed it important that if members were unable to take full advantage of their contractual right to earn additional pay, it was because they had “chosen to become and remain union members.” Id., at 435 (emphasis added).
The decision in NLRB v. Textile Workers, 409 U. S. 213 (1972), also supports the Board’s view that § 8(b)(1)(A) prohibits unions from punishing members not free to resign. There, 31 employees resigned their union membership and resumed working during a strike. We held that fining these former members “restrained or coerced” them, within the meaning of § 8(b)(1)(A). In reaching this conclusion, we said that “the vitality of § 7 requires that the member be free to refrain in November from the actions he endorsed in May.” Id., at 217-218. Restrictions on the right to resign curtail the freedom that the Textile Workers Court deemed so important. See also Machinists v. NLRB, 412 U. S. 84 (1973).
HI
Section 8(b)(1)(A) allows unions to enforce only those rules that “impai[r] no policy Congress has imbedded in the labor laws . . . .” Scofield, supra, at 430. The Board has found union restrictions on the right to resign to be inconsistent with the policy of voluntary unionism implicit in § 8(a)(3).14 [105]*105See International Assn. of Machinists, Inc., Local 1)11 (Neufeld, Porsche-Audi, Inc.), supra; Machinists Local 1327 (Dalmo Victor II), 263 N. L. R. B., at 992 (Chairman Van de Water and Member Hunter, concurring). We believe that the inconsistency between union restrictions on the right to resign and the policy of voluntary unionism supports the Board’s conclusion that League Law 13 is invalid.
Closed shop agreements, legalized by the Wagner Act in 1935,15 became quite common in the early 1940’s. Under these agreements, employers could hire and retain in their employ only union members in good standing. R. Gorman, [106]*106Labor Law, ch. 28, § 1, p. 639 (1976). Full union membership was thus compulsory in a closed shop; in order to keep their jobs, employees were required to attend union meetings, support union leaders, and otherwise adhere to union rules. Because of mounting objections to the closed shop, in 1947 — after hearings and full consideration — Congress enacted the Taft-Hartley Act. Section 8(a)(3) of that Act effectively eliminated compulsory union membership by outlawing the closed shop. The union security agreements permitted by § 8(a)(3) require employees to pay dues, but an employee cannot be discharged for failing to abide by union rules or policies with which he disagrees.16
Full union membership thus no longer can be a requirement of employment. If a new employee refuses formally to join a union and subject himself to its discipline, he cannot be fired. Moreover, no employee can be discharged if he initially joins a union, and subsequently resigns. We think it noteworthy that § 8(a)(3) protects the employment rights of the dissatisfied member, as well as those of the worker who never assumed full union membership. By allowing employees to resign from a union at any time, § 8(a)(3) protects the employee whose views come to diverge from those of his union.
League Law 13 curtails this freedom to resign from full union membership. Nevertheless, petitioners contend [107]*107that League Law 13 does not contravene the policy of voluntary unionism imbedded in the Act. They assert that this provision does not interfere with workers’ employment rights because offending members are not discharged, but only fined. We find this argument unpersuasive, for a union has not left a “worker’s employment rights inviolate when it exacts [his entire] paycheck in satisfaction of a fine imposed for working. ” Wellington, Union Fines and Workers’ Rights, 85 Yale L. J. 1022, 1023 (1976). Congress in 1947 sought to eliminate completely any requirement that the employee maintain full union membership.17 Therefore, the Board was justified in concluding that by restricting the right of employees to resign, League Law 13 impairs the policy of voluntary unionism.
1 — 1 <3
We now consider specifically three arguments advanced by petitioners: (i) union rules restricting the right to resign are protected by the proviso to § 8(b)(1)(A); (ii) the legislative history of the Act shows that Congress did not intend to protect the right of union members to resign; and (iii) labor unions should be allowed to restrict the right to resign because other voluntary associations are permitted to do so.18
[108]*108A
Petitioners first argue that the proviso to § 8(b)(1)(A) expressly allows unions to place restrictions on the right to resign. The proviso states that nothing in § 8(b)(1)(A) shall “impair the right of a labor organization to prescribe its own rules with respect to the acquisition or retention of membership therein.” 29 U. S. C. § 158(b)(1)(A). Petitioners contend that because League Law 18 places restrictions on the right to withdraw from the union, it is a “rul[e] with respect to the . . . retention of membership,” within the meaning of the proviso.19
Neither the Board nor this Court has ever interpreted the proviso as allowing unions to make rules restricting the right [109]*109to resign.20 Rather, the Court has assumed that “rules "with respect to the . . . retention of membership” are those that provide for the expulsion of employees from the union.21 The legislative history of the Taft-Hartley Act is consistent with this interpretation. Senator Holland, the proviso’s sponsor, stated that § 8(b)(1)(A) should not outlaw union rules “which ha[ve] to do with the admission or the expulsion of members.” 93 Cong. Rec. 4271 (1947) (emphasis added). Senator Taft accepted the proviso, for he likewise believed that a union should be free to “refuse [a] man admission to the union, or expel him from the union” Id., at 4272 (emphasis added). Furthermore, the legislative history of the Labor-Management Reporting and Disclosure Act of 1959, 29 U. S. C. §401 et seq., confirms that the proviso was intended to protect union rules involving admission and expulsion.22 [110]*110Accordingly, we find no basis for refusing to defer to the Board’s conclusion that League Law 13 is not a “rule with respect to the retention of membership,” within the meaning of the proviso.
B
The petitioners next argue that the legislative history of the Taft-Hartley Act shows that Congress made a considered decision not to protect union members’ right to resign. Section 8(c) of the House bill contained a detailed “bill of rights” for labor union members. H. R. 3020, § 8(c), 80th Cong., 1st Sess., 22-26 (1947). Included was a provision making it an unfair labor practice to “deny to any [union] member the right to resign from the organization at any time.” H. R. 3020, supra, § 8(c)(4), at 23. The Senate bill, on the other hand, did not set forth specific employee rights, but stated more generally that it was an unfair labor practice to “restrain or coerce” employees in the exercise of their §7 rights. H. R. 3020, 80th Cong., 1st Sess., §8(b)(1)(A), p. 81 (1947) (as passed by Senate). The Taft-Hartley Act contains the Senate bill’s general language rather than the more specific House prohibitions. See 29 U. S. C. § 158(b)(1)(A). The petitioners contend that the omission of the House provision shows that Congress expressly decided not to protect the “right to resign.”
The legislative history does not support this contention. The “right to resign” apparently was included in the original House bill to protect workers unable to resign because of “closed shop” agreements. Union constitutions limiting the right to resign were uncommon in 1947, see n. 12, supra; closed shop agreements, however, often impeded union resignations. The House Report, H. R. Rep. No. 245, 80th Cong., 1st Sess. (1947), confirms that closed shop agreements provided the impetus for the inclusion of a right to resign in [111]*111the House bill. The Report simply states that even under the proposed legislation, employees could be required to pay dues pursuant to union security agreements. Id., at 32. Because the closed shop was outlawed by the Taft-Hartley Act, see § 8(a)(3), 29 U. S. C. § 158(a)(3), it is not surprising that Congress thought it unnecessary explicitly to preserve the right to resign.
Even if § 8(c)(4) of the House bill, H. R. 3020, supra, was directed at restrictive union rules, its omission from the Taft-Hartley Act does not convince us that the Board’s construction of § 8(b)(1)(A) is unreasonable. The House Conference Report, upon which petitioners primarily rely, does state that the specific prohibitions of § 8(c) were “omitted . . . as unfair labor practices,” H. R. Conf. Rep. No. 510, 80th Cong., 1st Sess., 46 (1947). But this language does not suggest that all employee rights arguably protected by the House bill were to be left unprotected. Cf. id., at 43 (“[T]he primary strike for recognition . . . was not prohibited”). Apparently, the Report was intended merely to inform House Members that the detailed prohibitions of § 8(c) were not separately included in the conference bill as “unfair labor practices.” We are reluctant to reach a contrary conclusion, and thereby overturn the Board’s decision, on the basis of this summary statement in the House Conference Report. Congress must have been aware that the broad language of § 8(b)(1)(A) would reach some of the same union conduct proscribed by the detailed “bill of rights.”23
[112]*112Petitioners concede that “absent the legislative history,” the Board’s construction of § 8(b)(1)(A) would be entitled to deference. Tr. of Second Oral Arg. 15 (Apr. 1985). They argue, however, that “in this instance the legislative materials are too clearly opposed to what the Board did to permit the result the Board reached.” Id., at 17. We do not agree. The ambiguous legislative history upon which petitioners rely falls far short of showing that the Board’s interpretation of the Act is unreasonable.24
In Textile Workers, 409 U. S, at 216, and Machinists, 412 U. S., at 88 (per curiam), the Court stated that when a union constitution does not purport to restrict the right to resign, the “law which normally is reflected in our free institutions” is applicable. Relying on this quoted language, petitioners [113]*113argue that League Law 13 is valid. They assert that because the common law does not prohibit restrictions on resignation,25 such provisions are not violative of § 8(b)(1)(A) of the Act. We find no merit in this argument. Textile Workers, supra, and Machinists, supra, held only that in the absence of restrictions on the right to resign, members are free to leave the union at any time. Although the Court noted that its decisions were consistent with the common-law rule, it did not state that the validity of restrictions on the right to resign should be determined with reference to common law.
The Court’s decision in NLRB v. Marine & Shipbuilding Workers, 391 U. S. 418 (1968), demonstrates that many union rules, although valid under the common law of associations, run afoul of § 8(b)(1)(A) of the Act.26 There the union ex[114]*114pelled a member who failed to comply with a rule requiring the “exhaustion of] all remedies and appeals within the Union . . . before . . . resort to any court or other tribunal outside of the Union.” Id., at 421. Under the common law, associations may require their members to exhaust all internal remedies. See, e. g., Medical Soc. of Mobile Cty. v. Walker, 245 Ala. 135, 16 So. 2d 321 (1944). Nevertheless, the Marine Workers Court held that “considerations of public policy” mandated a holding that the union rule requiring exhaustion violated § 8(b)(1)(A), 29 U. S. C. § 158(b)(1)(A). 391 U. S., at 424; see also Scofield v. NLRB, 394 U. S., at 430 (union rule is invalid under § 8(b)(1)(A) if it “impairs [a] policy Congress has imbedded in the labor laws”).
The Board reasonably has concluded that League Law 13 “restrains or coerces” employees, see § 8(b)(1)(A), and is inconsistent with the congressional policy of voluntary unionism. Therefore, whatever may have been the common law, the Board’s interpretation of the Act merits our deference.
V
The Board has the primary responsibility for applying “ ‘the general provisions of the Act to the complexities of industrial life.’” Ford Motor Co. v. NLRB, 441 U. S. 488, 496 (1979), quoting NLRB v. Erie Resistor Corp., 373 U. S. 221, 236 (1963), in turn citing NLRB v. Steelworkers, 357 U. S. 357, 362-363 (1958). Where the Board’s construction of the Act is reasonable, it should not be rejected “merely because the courts might prefer another view of the statute.” Ford Motor Co. v. NLRB, supra, at 497. In this case, two factors suggest that we should be particularly reluctant to hold that the Board’s interpretation of the Act is impermissible. [115]*115First, in related cases this Court invariably has yielded to Board decisions on whether fines imposed by a union “restrain or coerce” employees.27 Second, the Board consistently has construed § 8(b)(1)(A) as prohibiting the imposition of fines on employees who have tendered resignations invalid under a union constitution.28 Therefore, we conclude that the Board’s decision here is entitled to our deference.
f — t >
The Board found that by fining employees who had tendered resignations, the petitioners violated § 8(b)(1)(A) of the [116]*116Act, even though League Law 13 purported to render the resignations ineffective. We defer to the Board’s interpretation of the Act and so affirm the judgment of the Court of Appeals enforcing the Board’s order.
It is so ordered.