Me. Justice White
delivered the opinion of the Court.
Petitioners, recipients of public assistance under the cooperative federal-state Aid to Families With Dependent Children (AFDC) program,1 brought this action in the District Court for themselves and their infant children and as representatives of other similarly situated AFDC recipients. Their suit challenged a provision of [531]*531the New York Code of Rules and Regulations permitting the State to recoup prior unscheduled payments for rent from subsequent grants under the AFDC program.2 They alleged that the recoupment regulation violated the Equal Protection Clause of the Fourteenth Amendment and contravened the pertinent provisions of the Social Security Act governing AFDC and the regulations promulgated thereunder by the administering federal agency, the Department of Health, Education, and Welfare (HEW).3 The action sought injunctive and declaratory [532]*532relief pursuant to 42 U. S. C. § 1983 and 28 U. S. C. § 2201, and jurisdiction was invoked under 28 U. S. C. §§ 1343 (3) and (4). The District Court found that the equal protection claim was substantial and provided a basis for pendent jurisdiction to adjudicate the so-called “statutory” claim — the alleged conflict between state and federal law. After hearing, the trial court declared the recoupment regulation contrary to the Social Security Act and HEW regulations and enjoined its implementa[533]*533tion or enforcement. Following a remand,4 the Court of Appeals reversed, holding that because petitioners had failed to present a substantial constitutional claim, the District Court lacked jurisdiction to entertain either the equal protection or the statutory claim. 471 F. 2d 347 (CA2 1973). The jurisdictional question being an important one, we granted certiorari. 412 U. S. 938 (1973). For reasons set forth below, we hold that the District Court had jurisdiction under 28 U. S. C. § 1343 (3) to consider petitioners’ attack on the recoupment regulation.5
[534]*534I
Petitioners brought this action under 42 U. S. C. § 1983, which provides:
“Every person who, under color of any statute, ordinance, regulation, custom, or usage, of any State [535]*535or Territory, subjects, or causes to be subjected, any citizen of the United States or other person within the jurisdiction thereof to the deprivation of any rights, privileges, or immunities secured by the Constitution and laws, shall be liable to the party injured in an action at law, suit in equity, or other proper proceeding for redress.”
By its terms, § 1983 embraces petitioners’ claims that the challenged regulation enforced by respondent state and county welfare officials deprives them of a right “secured by the Constitution and laws,” viz., the equal protection of the laws. But the federal cause of action created by the section does not by itself confer jurisdiction upon the federal district courts to adjudicate these claims. Accordingly, petitioners relied principally upon 28 U. S. C. § 1343 (3):
“The district courts shall have original jurisdic[536]*536tion of any civil action authorized by law to be commenced by any person:
“(3) To redress the deprivation, under color of any State law, statute, ordinance, regulation, custom or usage, of any right, privilege or immunity secured by the Constitution of the United States or by any Act of Congress providing for equal rights of citizens or of all persons within the jurisdiction of the United States . . .
Concededly, § 1343 authorizes a civil action to “redress the deprivation, under color of any State . . . regulation ... of any right . . . secured by the Constitution of the United States." Section 1343 (3) therefore conferred jurisdiction upon the District Court to entertain the constitutional claim if it was of sufficient substance to support federal jurisdiction. If it was, it is also clear that the District Court could hear as a matter of pendent jurisdiction the claim of conflict between federal and state law, without determining that the latter claim in its own right was encompassed within § 1343. Rosado v. Wyman, 397 U. S. 397, 402-405 (1970); see also N. Y. Dept. of Social Services v. Dublino, 413 U. S. 405, 412 n. 11 (1973).
The Court of Appeals ruled that petitioners had not tendered a substantial constitutional claim and ordered dismissal of the entire action for want of subject matter jurisdiction. The principle applied by the Court of Appeals — that a “substantial” question was necessary to support jurisdiction — was unexceptionable under prior cases. Over the years this Court has repeatedly held that the federal courts are without power to entertain claims otherwise within their jurisdiction if they are “so attenuated and unsubstantial as to be absolutely devoid of merit,” Newburyport Water Co. v. Newburyport, 193 [537]*537U. S. 561, 579 (1904); “wholly insubstantial,” Bailey v. Patterson, 369 U. S. 31, 33 (1962); “obviously frivolous,” Hannis Distilling Co. v. Baltimore, 216 U. S. 285, 288 (1910); “plainly unsubstantial,” Levering & Garrigues Co. v. Morrin, 289 U. S. 103, 105 (1933); or “no longer open to discussion,” McGilvra v. Ross, 215 U. S. 70, 80 (1909). One of the principal decisions on the subject, Ex ;parte Poresky, 290 U. S. 30, 31-32 (1933), held, first, that “[i]n the absence of diversity of citizenship, it is essential to jurisdiction that a substantial federal question should be presented”; second, that a three-judge court was not necessary to pass upon this initial question of jurisdiction; and third, that “[t]he question may be plainly unsubstantial, either because it is 'obviously without merit’ or because 'its unsoundness so clearly results from the previous decisions of this court as to foreclose the subject and leave no room for the inference that the question sought to be raised can be the subject of controversy.’ Levering & Garrigues Co. v.” Morrin, supra; Hannis Distilling Co. v. Baltimore, 216 U. S. 285, 288; McGilvra v. Ross, 215 U. S. 70, 80.”
Only recently this Court again reviewed this general question where it arose in the context of convening a three-judge court under 28 U. S. C. § 2281:
“ 'Constitutional insubstantiality’ for this purpose has been equated with such concepts as ‘essentially fictitious,’ Bailey v. Patterson, 369 U. S., at 33; ‘wholly insubstantial,’ ibid,.; ‘obviously frivolous,’ Hannis Distilling Co. y. Baltimore, 216 U. S. 285, 288 (1910); and ‘obviously without merit,’ Ex parte Poresky, 290 U. S. 30, 32 (1933). The limiting words ‘wholly’ and ‘obviously’ have cogent legal significance. In the context of the effect of prior decisions upon the substantiality of constitutional claims, those words import that claims are constitu[538]*538tionally insubstantial only if the prior decisions inescapably render the claims frivolous; previous decisions that merely render claims of doubtful or questionable merit do not render them insubstantial for the purposes of 28 U. S. C. § 2281. A claim is insubstantial only if ' “its unsoundness so clearly results from the previous decisions of this court as to foreclose the subject and leave no room for the inference that the questions sought to be raised can be the subject of controversy.” ’ Ex parte Poresky, supra, at 32, quoting from Hannis Distilling Co. v. Baltimore, supra, at 288; see also Levering & Garri-gues Co. v. Morrin, 289 U. S. 103, 105-106 (1933); McGilvra v. Ross, 215 U. S. 70, 80 (1909).” Goosby v. Osser, 409 U. S. 512, 518 (1973).
The substantiality doctrine as a statement of jurisdictional principles affecting the power of a federal court to adjudicate constitutional claims has been questioned, Bell v. Hood, 327 U. S. 678, 683 (1946), and characterized as “more ancient than analytically sound,” Rosado v. Wyman, supra, at 404. But it remains the federal rule and needs no re-examination here, for we are convinced that within accepted doctrine petitioners' complaint alleged a constitutional claim sufficient to confer jurisdiction on the District Court to pass on the controversy.
Jurisdiction is essentially the authority conferred by Congress to decide a given type of case one way or the other. The Fair v. Kohler Die Co., 228 U. S. 22, 25 (1913). Here, §§ 1343 (3) and 1983 unquestionably authorized federal courts to entertain suits to redress the deprivation, under color of state law, of constitutional rights. It is also plain that the complaint formally alleged such a deprivation. The District Court’s jurisdiction, a matter for threshold determination, turned [539]*539on whether the question was too insubstantial for consideration.
In Dandridge v. Williams, 397 U. S. 471 (1970), AFDC recipients challenged the Maryland maximum grant regulation on equal protection grounds. We held that the issue should be resolved by inquiring whether the classification had a rational basis. Finding that it did, we sustained the regulation. But Dandridge evinced no intention to suspend the operation of the Equal Protection Clause in the field of social welfare law. State laws and regulations must still “be rationally based and free from invidious discrimination.” Id., at 487. See Jefferson v. Hackney, 406 U. S. 535, 546 (1972); Carter v. Stanton, 405 U. S. 669, 671 (1972); cf. San Antonio School District v. Rodriguez, 411 U. S. 1 (1973).
Judged by this standard, we cannot say that the equal protection issue tendered by the complaint was either frivolous or so insubstantial as to be beyond the jurisdiction of the District Court. We are unaware of any cases in this Court specifically dealing with this or any similar regulation and settling the matter one way or the other.6 Nor is it immediately obvious to us from the [540]*540face of the complaint that recouping emergency rent payments from future welfare disbursements, which petitioners argue deprived needy children because of parental [541]*541default, was so patently rational as to require no meaningful consideration.
The Court of Appeals rightly felt obliged to measure petitioners’ complaint that the challenged regulation violated the Equal Protection Clause “by discriminating irrationally and invidiously between different classes of recipients”7 against the standard prescribed by Dan-dridge. The Court of Appeals then reasoned that without the recoupment regulation, those who were subject to it would be preferred over those who had paid their full rent out of their normal monthly grant. The court further reasoned that the regulation provided an incentive for welfare recipients to properly manage their grants and not become delinquent in their rent.8 It concluded that [542]*542the regulation was rationally based and that no substantial constitutional question within the jurisdiction of the District Court had been presented.
This reasoning with respect to the rationality of the regulation and its propriety under the Equal Protection Clause may ultimately prove correct, but it is not immediately obvious from the decided cases or so “very plain” 9 under the Equal Protection Clause. We think the admonition of Bell v. Hood, 327 U. S. 678 (1946), should be followed here:
“Jurisdiction ... is not defeated as respondents seem to contend, by the possibility that the aver-ments might fail to state a cause of action on which petitioners could actually recover. For it is well settled that the failure to state a proper cause of action calls for a judgment on the merits and not for a dismissal for want of jurisdiction. Whether the complaint states a cause of action on which relief could be granted is a question of law and just as issues of fact it must be decided after and not before the court has assumed jurisdiction over the controversy. If the court does later exercise its jurisdiction to determine that the allegations in the complaint do not state a ground for relief, then dismissal of the case would be on the merits, not for want of jurisdiction.” Id., at 682 (citations omitted).10
As was the case in Bell v. Hood, we cannot “say that the cause of action alleged is so patently without merit [543]*543as to justify, even under the qualifications noted, the court’s dismissal for want of jurisdiction.” Id., at 683. Nor can we say that petitioners’ claim is "so insubstantial, implausible, foreclosed by prior decisions of this Court or otherwise completely devoid of merit as not to involve a federal controversy within the jurisdiction of the District Court, whatever may be the ultimate resolution of the federal issues on the merits.” Oneida Indian Nation v. County of Oneida, 414 U. S. 661, 666-667 (1974). (Citations omitted.)
II
Given a constitutional question over which the District Court had jurisdiction, it also had jurisdiction over the “statutory” claim. See supra, at 536. The latter was to be decided first and the former not reached if the statutory claim was dispositive. California Human Resources Dept. v. Java, 402 U. S. 121, 124 (1971); Dandridge v. Williams, 397 U. S., at 475-476; Rosado v. Wyman, 397 U. S., at 402; King v. Smith, 392 U. S. 309 (1968). The constitutional claim could be adjudicated only by a three-judge court, but the statutory claim was within the jurisdiction of a single district judge. Swift & Co.v. Wickham, 382 U. S. Ill (1965); Rosado v. Wyman, supra, at 403. Thus, the District Judge, sitting alone, moved directly to the statutory claim. His decision was appealed to the Court of Appeals, although had a three-judge court been convened, an injunction issued, and the statutory ground alone decided, the appeal would be only to this Court under 28 U. S. C. § 1253.
The procedure followed by the District Court — initial determination of substantiality and then adjudication of the “statutory” claim without convening a three-judge court — may appear at odds with some of our prior decisions. See, e. g., Engineers v. Chicago, R. I. & P. R. Co., 382 U. S. 423 (1966); Florida Lime & Avocado Grow[544]*544ers v. Jacobsen, 362 U. S. 73 (1960). But, we think it accurately reflects the recent evolution of three-judge-court jurisprudence, “this Court's concern for efficient operation of the lower federal courts,” and “the constrictive view of the three-judge [court] jurisdiction which this Court has traditionally taken.” Swift & Co. v. Wickham, supra, at 128, 129 (citations omitted). In Rosado v. Wyman, supra, at 403, we suggested that
“[e]ven had the constitutional claim not been declared moot, the most appropriate course may well have been to remand to the single district judge for findings and the determination of the statutory claim rather than encumber the district court, at a time when district court calendars are overburdened, by consuming the time of three federal judges in a matter that was not required to be determined by a three-judge court. See Swift & Co. v. Wickham, 382 U. S. Ill (1965).”
It is true that the constitutional claim would warrant convening a three-judge court and that if a single judge rejects the statutory claim, a three-judge court must be called to consider the constitutional issue. Nevertheless, the coincidence of a constitutional and statutory claim should not automatically require a single-judge district court to defer to a three-judge panel, which, in view of what we have said in Rosado v. Wyman, supra, could then merely pass the statutory claim back to the single judge. See Kelly v. Illinois Bell Telephone Co., 325 F. 2d 148, 151 (CA7 1963); Chicago, Duluth & Georgian Bay Transit Co. v. Nims, 252 F. 2d 317, 319-320 (CA6 1958); Doe v. Lavine, 347 F. Supp. 357, 359-360 (SDNY 1972); cf. Bryant v. Carleson, 444 F. 2d 353, 358-359 (CA9 1971). “In fact, it would be grossly inefficient to send a three-judge court a claim which will only be sent immediately back. This inefficiency is especially [545]*545apparent if the single judge’s decision resolves the case, for there is then no need to convene the three-judge court.” Norton v. Richardson, 352 F. Supp. 596, 599 (Md. 1972) (citations omitted). Section 2281 does not forbid this practice, and we are not inclined to read that statute “in isolation with mutilating literalness . . . .” Florida Lime & Avocado Growers v. Jacobsen, supra, at 94 (Frankfurter, J., dissenting).
Ill
Taking a jaundiced view of the constitutional claim, the dissenters would have the District Court dismiss the Supremacy Clause (“statutory”) issue, convene a three-judge court, and reject the constitutional claim, all of this, apparently, as an exercise of the discretion which the District Court, under Mine Workers v. Gibbs, 383 U. S. 715 (1966), is claimed to have over the pendent federal claim. But Gibbs was oriented to state law claims pendent to federal claims conferring jurisdiction on the District Court. Pendent jurisdiction over state claims was described as a doctrine of discretion not to be routinely exercised without considering the advantages of judicial economy, convenience, and fairness to litigants. For, “[n]eedless decisions of state law should be avoided both as a matter of comity and to promote justice between the parties, by procuring for them a surer-footed reading of applicable law.” Id., at 726 (footnote omitted).11
In light of the dissent’s treatment of Gibbs, several observations are appropriate. First, it is evident from Gibbs that pendent state law claims are not always, or even almost always, to be dismissed and not adjudicated. [546]*546On the contrary, given advantages of economy and convenience and no unfairness to litigants, Gibbs contemplates adjudication of these claims.
Second, it would reasonably follow that other considerations may warrant adjudication rather than dismissal of pendent state claims. In Siler v. Louisville & Nashville R. Co., 213 U. S. 175 (1909) the Court held that the state issues should be decided first and because these claims were dispositive, federal questions need not be reached:
“Where a case in this court can be decided without reference to questions arising under the Federal Constitution, that course is usually pursued and is not departed from without important reasons. In this case we think it much better to decide it with regard to the question of a local nature, involving the construction of the state statute and the authority therein given to the commission to make the order in question, rather than to unnecessarily decide the various constitutional questions appearing in the record.” Id., at 193.
Siler is not an oddity. The Court has characteristically dealt first with possibly dispositive state law claims pendent to federal constitutional claims. See, e. g., Louisville & Nashville R. Co. v. Garrett, 231 U. S. 298, 303-304, 310 (1913); Ohio Tax Cases, 232 U. S. 576, 586-587 (1914); Greene v. Louisville & Interurban R. Co., 244 U. S. 499, 508-509 (1917); Louisville & Nashville R. Co. v. Greene, 244 U. S. 522, 527 (1917); Davis v. Wallace, 257 U. S. 478, 482, 485 (1922); Chicago G. W. R. Co. v. Kendall, 266 U. S. 94, 97-98 (1924); Cincinnati v. Vester, 281 U. S. 439, 448-449 (1930); Hillsborough v. Cromwell, 326 U. S. 620, 629 (1946). The doctrine is not ironclad, see Sterling v. Constantin, 287 U. S. 378, 393-394, 396 (1932), but it is recurringly ap[547]*547plied,12 and, at the very least, it presumes the advisability of deciding first the pendent, nonconstitutional issue.
Gibbs did not cite Siler or like cases, nor did it purport to change the ordinary rule that a federal court should not decide federal constitutional questions where a dis-positive nonconstitutional ground is available. The dissent uncritically relies on Siler but ignores the preference stated in that case for deciding nonconstitutional claims even though they are pendent and, standing alone, are beyond the jurisdiction of the federal court.13
[548]*548Third, the rationale of Gibbs centers upon considerations of comity and the desirability of having a reliable and final determination of the state claim by state courts having more familiarity with the controlling principles and the authority to render a final judgment. These considerations favoring state adjudication are wholly irrelevant where the pendent claim is federal but is itself beyond the jurisdiction of the District Court for failure to satisfy the amount in controversy. In such cases, the federal court’s rendition of federal law will be at least as sure-footed and lasting as any judgment from the state courts.14
[549]*549The most relevant cases for our purposes, of course, are those decisions such as King v. Smith, 392 U. S. 309 (1968), Rosado v. Wyman, 397 U. S. 397 (1970), and Dandridge v. Williams, 397 U. S. 471 (1970), where the jurisdictional claim arises under the Federal Constitution and the pendent claim, although denominated “statutory,” is in reality a constitutional claim arising under the Supremacy Clause. In these cases the Court has characteristically dealt with the “statutory” claim first “because if the appellees’ position on this question is correct, there is no occasion to reach the constitutional issues. Ashwander v. TV A, 297 U. S. 288, 346-347 (Brandéis, J., concurring); Rosenberg v. Fleuti, 374 U. S. 449.” Dandridge v. Williams, supra, at 475-476.
In none of these cases did the Court think that with jurisdiction fairly established, a federal court, [550]*550under Gibbs, must nevertheless decide the constitutional issue and avoid the statutory claim if, upon weighing the two claims, the statutory claim is strong and the constitutional claim weak. On the contrary, Mr. Justice Harlan, writing for the Court in Rosado v. Wyman, and with the principles of Gibbs well in mind, noted that the pendent statutory question was essentially one of federal policy and that the argument for the exercise of pendent jurisdiction was “ ‘particularly strong.’ ” 397 U. S., at 404. And Gibbs itself observed the “special reason for the exercise of pendent jurisdiction” where the Supremacy Clause is implicated: “the federal courts are particularly appropriate bodies for the application of pre-emption principles.” 383 U. S., at 729.
The judgment of the Court of Appeals is reversed and the case remanded to that court for further proceedings consistent with this opinion.
So ordered.