MR. JUSTICE BLACKMUN delivered the opinion of the Court.

The Indian Reorganization Act of 1934, also known as the Wheeler-Howard Act, 48 Stat. 984, 25 U.S.C. § 461 et seq., accords an employment preference for qualified Indians in the Bureau of Indian Affairs (BIA or Bureau). Appellees, non-Indian BIA employees, challenged this preference as contrary to the anti-discrimination provisions of the Equal Employment Opportunity Act of 1972, 86 Stat. 103, 42 U.S.C. § 2000e et seq. (1970 ed., Supp. II), and as violative of the Due Process Clause of the Fifth Amendment. A three-judge Federal District Court concluded that the Indian preference under the 1934 Act was impliedly repealed by the 1972 Act. 359 F. Supp. 585 (NM 1973). We noted probable jurisdiction in order to examine the statutory and constitutional validity of this longstanding Indian preference. 414 U.S. 1142 (1974); 415 U.S. 946 (1974).

I

Section 12 of the Indian Reorganization Act, 48 Stat. 986, 25 U.S.C. § 472, provides:

"The Secretary of the Interior is directed to establish standards of health, age, character, experience, knowledge, and ability for Indians who may be appointed, without regard to civil-service laws, to the various positions maintained, now or hereafter, by the Indian Office, in the administration of functions or services affecting any Indian tribe. Such qualified Indians shall hereafter have the preference to appointment to vacancies in any such positions."

In June 1972, pursuant to this provision, the Commissioner of Indian Affairs, with the approval of the Secretary of the Interior, issued a directive (Personnel Management Letter No. 72-12) (App. 52) stating that the BIA's policy would be to grant a preference to qualified Indians not only, as before, in the initial hiring stage, but also in the situation where an Indian and a non-Indian, both already employed by the BIA, were competing for a promotion within the Bureau. The record indicates that this policy was implemented immediately.

Shortly thereafter, appellees, who are non-Indian employees of the BIA at Albuquerque, instituted this class action, on behalf of themselves and other non-Indian employees similarly situated, in the United States District Court for the District of New Mexico, claiming that the "so-called `Indian Preference Statutes,'" App. 15, were repealed by the 1972 Equal Employment Opportunity Act and deprived them of rights to property without due process of law, in violation of the Fifth Amendment. Named as defendants were the Secretary of the Interior, the Commissioner of Indian Affairs, and the BIA Directors for the Albuquerque and Navajo Area Offices. Appellees claimed that implementation and enforcement of the new preference policy "placed and will continue to place [appellees] at a distinct disadvantage in competing for promotion and training programs with Indian employees, all of which has and will continue to subject the [appellees] to discrimination and deny them equal employment opportunity." App. 16.

A three-judge court was convened pursuant to 28 U.S.C. § 2282 because the complaint sought to enjoin, as unconstitutional, the enforcement of a federal statute. Appellant Amerind, a nonprofit organization representing Indian employees of the BIA, moved to intervene in support of the preference; this motion was granted by the District Court and Amerind thereafter participated at all stages of the litigation.

After a short trial focusing primarily on how the new policy, in fact, has been implemented, the District Court concluded that the Indian preference was implicitly repealed by § 11 of the Equal Employment Opportunity Act of 1972, Pub.L. 92-261, 86 Stat. 111, 42 U.S.C. § 2000e-16 (a) (1970 ed., Supp. II), proscribing discrimination in most federal employment on the basis of race. Having found that Congress repealed the preference, it was unnecessary for the District Court to pass on its constitutionality. The court permanently enjoined appellants "from implementing any policy in the Bureau of Indian Affairs which would hire, promote, or reassign any person in preference to another solely for the reason that such person is an Indian." The execution and enforcement of the judgment of the District Court was stayed by MR. JUSTICE MARSHALL on August 16, 1973, pending the disposition of this appeal.

II

The federal policy of according some hiring preference to Indians in the Indian service dates at least as far back as 1834. Since that time, Congress repeatedly has enacted various preferences of the general type here at issue. The purpose of these preferences, as variously expressed in the legislative history, has been to give Indians a greater participation in their own self-government; to further the Government's trust obligation toward the Indian tribes; and to reduce the negative effect of having non-Indians administer matters that affect Indian tribal life.

The preference directly at issue here was enacted as an important part of the sweeping Indian Reorganization Act of 1934. The overriding purpose of that particular Act was to establish machinery whereby Indian tribes would be able to assume a greater degree of self-government, both politically and economically. Congress was seeking to modify the then-existing situation whereby the primarily non-Indian-staffed BIA had plenary control, for all practical purposes, over the lives and destinies of the federally recognized Indian tribes. Initial congressional proposals would have diminished substantially the role of the BIA by turning over to federally chartered self-governing Indian communities many of the functions normally performed by the Bureau. Committee sentiment, however, ran against such a radical change in the role of the BIA. The solution ultimately adopted was to strengthen tribal government while continuing the active role of the BIA, with the understanding that the Bureau would be more responsive to the interests of the people it was created to serve.

One of the primary means by which self-government would be fostered and the Bureau made more responsive was to increase the participation of tribal Indians in the BIA operations. In order to achieve this end, it was recognized that some kind of preference and exemption from otherwise prevailing civil service requirements was necessary. Congressman Howard, the House sponsor, expressed the need for the preference:

"The Indians have not only been thus deprived of civic rights and powers, but they have been largely deprived of the opportunity to enter the more important positions in the service of the very bureau which manages their affairs. Theoretically, the Indians have the right to qualify for the Federal civil service. In actual practice there has been no adequate program of training to qualify Indians to compete in these examinations, especially for technical and higher positions; and even if there were such training, the Indians would have to compete under existing law, on equal terms with multitudes of white applicants. . . . The various services on the Indian reservations are actually local rather than Federal services and are comparable to local municipal and county services, since they are dealing with purely local Indian problems. It should be possible for Indians with the requisite vocational and professional training to enter the service of their own people without the necessity of competing with white applicants for these positions. This bill permits them to do so." 78 Cong. Rec. 11729 (1934).

Congress was well aware that the proposed preference would result in employment disadvantages within the BIA for non-Indians. Not only was this displacement unavoidable if room were to be made for Indians, but it was explicitly determined that gradual replacement of non-Indians with Indians within the Bureau was a desirable feature of the entire program for self-government. Since 1934, the BIA has implemented the preference with a fair degree of success. The percentage of Indians employed in the Bureau rose from 34% in 1934 to 57% in 1972. This reversed the former downward trend, see n. 16, supra, and was due, clearly, to the presence of the 1934 Act. The Commissioner's extension of the preference in 1972 to promotions within the BIA was designed to bring more Indians into positions of responsibility and, in that regard, appears to be a logical extension of the congressional intent. See Freeman v. Morton, 162 U.S.App.D.C. 358, 499 F.2d 494 (1974), and n. 5, supra.

III

It is against this background that we encounter the first issue in the present case: whether the Indian preference was repealed by the Equal Employment Opportunity Act of 1972. Title VII of the Civil Rights Act of 1964, 78 Stat. 253, was the first major piece of federal legislation prohibiting discrimination in private employment on the basis of "race, color, religion, sex, or national origin." 42 U.S.C. § 2000e-2 (a). Significantly, §§ 701(b) and 703(i) of that Act explicitly exempted from its coverage the preferential employment of Indians by Indian tribes or by industries located on or near Indian reservations. 42 U.S.C. § 2000e (b) and 2000e-2(i). This exemption reveals a clear congressional recognition, within the framework of Title VII, of the unique legal status of tribal and reservation-based activities. The Senate sponsor, Senator Humphrey, stated on the floor by way of explanation:

"This exemption is consistent with the Federal Government's policy of encouraging Indian employment and with the special legal position of Indians." 110 Cong. Rec. 12723 (1964).

The 1964 Act did not specifically outlaw employment discrimination by the Federal Government. Yet the mechanism for enforcing longstanding Executive Orders forbidding Government discrimination had proved ineffective for the most part. In order to remedy this, Congress, by the 1972 Act, amended the 1964 Act and proscribed discrimination in most areas of federal employment. See n. 6, supra. In general, it may be said that the substantive anti-discrimination law embraced in Title VII was carried over and applied to the Federal Government. As stated in the House Report:

"To correct this entrenched discrimination in the Federal service, it is necessary to insure the effective application of uniform, fair and strongly enforced policies. The present law and the proposed statute do not permit industry and labor organizations to be the judges of their own conduct in the area of employment discrimination. There is no reason why government agencies should not be treated similarly . . . ." H.R. Rep. No. 92-238, on H.R. 1746, pp. 24-25 (1971).

Nowhere in the legislative history of the 1972 Act, however, is there any mention of Indian preference.

Appellees assert, and the District Court held, that since the 1972 Act proscribed racial discrimination in Government employment, the Act necessarily, albeit sub silentio, repealed the provision of the 1934 Act that called for the preference in the BIA of one racial group, Indians, over non-Indians:

"When a conflict such as in this case, is present, the most recent law or Act should apply and the conflicting Preferences passed some 39 years earlier should be impliedly repealed." Brief for Appellees 7.

We disagree. For several reasons we conclude that Congress did not intend to repeal the Indian preference and that the District Court erred in holding that it was repealed.

First: There are the above-mentioned affirmative provisions in the 1964 Act excluding coverage of tribal employment and of preferential treatment by a business or enterprise on or near a reservation. 42 U.S.C. § 2000e (b) and 2000e-2(i). See n. 19, supra. These 1964 exemptions as to private employment indicate Congress' recognition of the longstanding federal policy of providing a unique legal status to Indians in matters concerning tribal or "on or near" reservation employment. The exemptions reveal a clear congressional sentiment that an Indian preference in the narrow context of tribal or reservation-related employment did not constitute racial discrimination of the type otherwise proscribed. In extending the general anti-discrimination machinery to federal employment in 1972, Congress in no way modified these private employment preferences built into the 1964 Act, and they are still in effect. It would be anomalous to conclude that Congress intended to eliminate the longstanding statutory preferences in BIA employment, as being racially discriminatory, at the very same time it was reaffirming the right of tribal and reservation-related private employers to provide Indian preference. Appellees' assertion that Congress implicitly repealed the preference as racially discriminatory, while retaining the 1964 preferences, attributes to Congress irrationality and arbitrariness, an attribution we do not share.

Second: Three months after Congress passed the 1972 amendments, it enacted two new Indian preference laws. These were part of the Education Amendments of 1972, 86 Stat. 235, 20 U.S.C. § 887c (a) and (d), and § 1119a (1970 ed., Supp. II). The new laws explicitly require that Indians be given preference in Government programs for training teachers of Indian children. It is improbable, to say the least, that the same Congress which affirmatively approved and enacted these additional and similar Indian preferences was, at the same time, condemning the BIA preference as racially discriminatory. In the total absence of any manifestation of supportive intent, we are loathe to imply this improbable result.

Third: Indian preferences, for many years, have been treated as exceptions to Executive Orders forbidding Government employment discrimination. The 1972 extension of the Civil Rights Act to Government employment is in large part merely a codification of prior anti-discrimination Executive Orders that had proved ineffective because of inadequate enforcement machinery. There certainly was no indication that the substantive proscription against discrimination was intended to be any broader than that which previously existed. By codifying the existing anti-discrimination provisions, and by providing enforcement machinery for them, there is no reason to presume that Congress affirmatively intended to erase the preferences that previously had coexisted with broad anti-discrimination provisions in Executive Orders.

Fourth: Appellees encounter head-on the "cardinal rule . . . that repeals by implication are not favored." Posadas v. National City Bank, 296 U.S. 497, 503 (1936); Wood v. United States, 16 Pet. 342-343, 363 (1842); Universal Interpretive Shuttle Corp. v. Washington Metropolitan Area Transit Comm'n, 393 U.S. 186, 193 (1968). They and the District Court read the congressional silence as effectuating a repeal by implication. There is nothing in the legislative history, however, that indicates affirmatively any congressional intent to repeal the 1934 preference. Indeed, as explained above, there is ample independent evidence that the legislative intent was to the contrary.

This is a prototypical case where an adjudication of repeal by implication is not appropriate. The preference is a longstanding, important component of the Government's Indian program. The anti-discrimination provision, aimed at alleviating minority discrimination in employment, obviously is designed to deal with an entirely different and, indeed, opposite problem. Any perceived conflict is thus more apparent than real.

In the absence of some affirmative showing of an intention to repeal, the only permissible justification for a repeal by implication is when the earlier and later statutes are irreconcilable. Georgia v. Pennsylvania R. Co., 324 U.S. 439, 456-457 (1945). Clearly, this is not the case here. A provision aimed at furthering Indian self-government by according an employment preference within the BIA for qualified members of the governed group can readily co-exist with a general rule prohibiting employment discrimination on the basis of race. Any other conclusion can be reached only by formalistic reasoning that ignores both the history and purposes of the preference and the unique legal relationship between the Federal Government and tribal Indians.

Furthermore, the Indian preference statute is a specific provision applying to a very specific situation. The 1972 Act, on the other hand, is of general application. Where there is no clear intention otherwise, a specific statute will not be controlled or nullified by a general one, regardless of the priority of enactment. See, e.g., Bulova Watch Co. v. United States, 365 U.S. 753, 758 (1961); Rodgers v. United States, 185 U.S. 83, 87-89 (1902).

The courts are not at liberty to pick and choose among congressional enactments, and when two statutes are capable of co-existence, it is the duty of the courts, absent a clearly expressed congressional intention to the contrary, to regard each as effective. "When there are two acts upon the same subject, the rule is to give effect to both if possible . . . . The intention of the legislature to repeal `must be clear and manifest.'" United States v. Borden Co., 308 U.S. 188, 198 (1939). In light of the factors indicating no repeal, we simply cannot conclude that Congress consciously abandoned its policy of furthering Indian self-government when it passed the 1972 amendments.

We therefore hold that the District Court erred in ruling that the Indian preference was repealed by the 1972 Act.

IV

We still must decide whether, as the appellees contend, the preference constitutes invidious racial discrimination in violation of the Due Process Clause of the Fifth Amendment. Bolling v. Sharpe, 347 U.S. 497 (1954). The District Court, while pretermitting this issue, said: "[W]e could well hold that the statute must fail on constitutional grounds." 359 F. Supp., at 591.

Resolution of the instant issue turns on the unique legal status of Indian tribes under federal law and upon the plenary power of Congress, based on a history of treaties and the assumption of a "guardian-ward" status, to legislate on behalf of federally recognized Indian tribes. The plenary power of Congress to deal with the special problems of Indians is drawn both explicitly and implicitly from the Constitution itself. Article I, § 8, cl. 3, provides Congress with the power to "regulate Commerce . . . with the Indian Tribes," and thus, to this extent, singles Indians out as a proper subject for separate legislation. Article II, § 2, cl. 2, gives the President the power, by and with the advice and consent of the Senate, to make treaties. This has often been the source of the Government's power to deal with the Indian tribes. The Court has described the origin and nature of the special relationship:

"In the exercise of the war and treaty powers, the United States overcame the Indians and took possession of their lands, sometimes by force, leaving them an uneducated, helpless and dependent people, needing protection against the selfishness of others and their own improvidence. Of necessity, the United States assumed the duty of furnishing that protection, and with it the authority to do all that was required to perform that obligation and to prepare the Indians to take their place as independent, qualified members of the modern body politic. . . ." Board of County Comm'rs v. Seber, 318 U.S. 705, 715 (1943).

See also United States v. Kagama, 118 U.S. 375, 383-384 (1886).

Literally every piece of legislation dealing with Indian tribes and reservations, and certainly all legislation dealing with the BIA, single out for special treatment a constituency of tribal Indians living on or near reservations. If these laws, derived from historical relationships and explicitly designed to help only Indians, were deemed invidious racial discrimination, an entire Title of the United States Code (25 U.S.C.) would be effectively erased and the solemn commitment of the Government toward the Indians would be jeopardized. See Simmons v. Eagle Seelatsee, 244 F. Supp. 808, 814 n. 13 (ED Wash. 1965), aff'd, 384 U.S. 209 (1966).

It is in this historical and legal context that the constitutional validity of the Indian preference is to be determined. As discussed above, Congress in 1934 determined that proper fulfillment of its trust required turning over to the Indians a greater control of their own destinies. The overly paternalistic approach of prior years had proved both exploitative and destructive of Indian interests. Congress was united in the belief that institutional changes were required. An important part of the Indian Reorganization Act was the preference provision here at issue.

Contrary to the characterization made by appellees, this preference does not constitute "racial discrimination." Indeed, it is not even a "racial" preference. Rather, it is an employment criterion reasonably designed to further the cause of Indian self-government and to make the BIA more responsive to the needs of its constituent groups. It is directed to participation by the governed in the governing agency. The preference is similar in kind to the constitutional requirement that a United States Senator, when elected, be "an Inhabitant of that State for which he shall be chosen," Art. I, § 3, cl. 3, or that a member of a city council reside within the city governed by the council. Congress has sought only to enable the BIA to draw more heavily from among the constituent group in staffing its projects, all of which, either directly or indirectly, affect the lives of tribal Indians. The preference, as applied, is granted to Indians not as a discrete racial group, but, rather, as members of quasi-sovereign tribal entities whose lives and activities are governed by the BIA in a unique fashion. See n. 24, supra. In the sense that there is no other group of people favored in this manner, the legal status of the BIA is truly sui generis. Furthermore, the preference applies only to employment in the Indian service. The preference does not cover any other Government agency or activity, and we need not consider the obviously more difficult question that would be presented by a blanket exemption for Indians from all civil service examinations. Here, the preference is reasonably and directly related to a legitimate, nonracially based goal. This is the principal characteristic that generally is absent from proscribed forms of racial discrimination.

On numerous occasions this Court specifically has upheld legislation that singles out Indians for particular and special treatment. See, e.g., Board of County Comm'rs v. Seber, 318 U.S. 705 (1943) (federally granted tax immunity); McClanahan v. Arizona State Tax Comm'n, 411 U.S. 164 (1973) (same); Simmons v. Eagle Seelatsee, 384 U.S. 209 (1966), aff'g 244 F. Supp. 808 (ED Wash. 1965) (statutory definition of tribal membership, with resulting interest in trust estate); Williams v. Lee, 358 U.S. 217 (1959) (tribal courts and their jurisdiction over reservation affairs). Cf. Morton v. Ruiz, 415 U.S. 199 (1974) (federal welfare benefits for Indians "on or near" reservations). This unique legal status is of long standing, see Cherokee Nation v. Georgia, 5 Pet. 1 (1831); Worcester v. Georgia, 6 Pet. 515 (1832), and its sources are diverse. See generally U.S. Dept. of Interior, Federal Indian Law (1958); Comment, The Indian Battle for Self-Determination, 58 Calif. L. Rev. 445 (1970). As long as the special treatment can be tied rationally to the fulfillment of Congress' unique obligation toward the Indians, such legislative judgments will not be disturbed. Here, where the preference is reasonable and rationally designed to further Indian self-government, we cannot say that Congress' classification violates due process.

The judgment of the District Court is reversed and the cases are remanded for further proceedings consistent with this opinion.

It is so ordered.