One of the lesser-noted accomplishments of President Reagan's first year in office was his success in separating his economic program from a set of divisive civil rights and conservative social issues.

But today, pressure from the political right that helped elect Reagan, and a series of seemingly unrelated actions by his administration, has plunged the president into a far-reaching and potentially treacherous agenda on issues that deeply divide the nation.

The agenda includes efforts to end legalized abortion, ease enforcement of job discrimination laws, restore prayer in public schools, halt "judicial activism" in federal courts, alter the way school integration and voting rights cases are handled, and diminish federal efforts in seeking racial and sexual equality.

The agenda does not exist in any presidential pronouncement or legislative package. And there is no David Stockman of civil rights or social issues to frame an overall strategy. News Analysis News Analysis

But an unmistakable pattern emerges from the words and actions of the Reagan administration.

It involves the reversal of a host of actions by Republican and Democratic presidents, bipartisan majorities of Congress and federal courts during the last 25 years.

Among the recent moves:

* In 1972, the Supreme Court in Swann vs. Charlotte-Mecklenburg County unanimously ruled that busing and quotas were appropriate ways of ending school segregation. The case set public policy for almost a decade.

Under Reagan, the Justice Department has abandoned busing as a remedy in school desegregation cases, and reversed decisions on several sensitive desegregation plans. Last week, for example, it proposed a voluntary plan in Chicago that involves no mandatory busing.

* In 1964, the Civil Rights Act began a steady expansion of equal opportunity laws, including such affirmative action measures as quotas and timetables as remedies for job discrimination. The Equal Employment Opportunity Commission was set up that same year.

Under Reagan, the departments of Labor and Justice have taken steps to ban the use of quotas and generally eased enforcement. A recent Justice Department settlement of a New Hampshire state police case, for example, called for "recruitment goals" instead of quotas for hiring minorities and women.

Last week, Reagan named Clarence Thomas, a conservative black lawyer who has expressed serious reservations about the role of the EEOC, to head the agency.

* In 1957, under the Eisenhower administration, the Commission on Civil Rights was established as an independent, information-gathering body to serve as the conscience of the government on racial equality. Every president since has appointed well-known figures, including university presidents, former Cabinet members and former governors, to the commission.

Last week, Reagan broke that tradition by nominating B. Sam Hart, a black evangelist unknown to civil rights groups as well as Republican leaders in his home state, to the commission.

Hart, backed for the job by fundamentalist religious groups, said he opposes the Equal Rights Amendment, busing to integrate public schools and the concept of civil rights for homosexuals. Latest in a series of obscure blacks appointed to symbolic jobs, he is to replace Jill Ruckelshaus, a moderate Republican.

* In 1970, Richard M. Nixon approved a policy later followed by Gerald R. Ford and Jimmy Carter that denied tax-exempt status to private schools that discriminate.

Last month, the administration abandoned the policy, restoring tax exemptions for schools that discriminate against minorities. When the decision came under severe criticism, the president said he thought the matter should be dealt with by congressional rather than administrative action. He then proposed legislation to deny tax exemptions.

Since the mid-1960s, federal courts have repeatedly stepped into sensitive areas of public policy, such as racial discrimination and abortion, on grounds that issues involved are so fundamental that they cannot be left to majority rule.

Under Reagan, Attorney General William French Smith has led a well-orchestrated attack on "judicial activism." He has accused "unelected judges" of substituting "their own policy preferences for the determinations of the public's elected representatives."

He has also said federal courts have gone beyond their proper role in cases involving abortion, school busing, prison rights and other sensitive social policy issues.

* In 1965, President Johnson signed the Voting Rights Act, a landmark piece of legislation guaranteeing all Americans the right to vote. Widely regarded as the nation's most successful piece of civil rights legislation, the House last fall overwhelmingly voted to extend the act for another 10 years.

The Reagan administration opposes several key provisions of the bill, which has 63 Senate sponsors. It wants to make state and local election procedures illegal only if minorities can demonstrate they are discriminatory in "intent," and not simply in effect. It also supports provisions that would make it easier for areas to "bail out" from coverage.

The administration has also reversed prior decisions in several voting rights cases. Last summer, the Justice Department withdrew objections it had first raised in 1976 to efforts by the city of Jackson, Miss., to annex white suburbs, a change that would dilute black votes in the city's at-large election system.

It also unexpectedly reversed its position in a voting rights suit in Edgefield, S.C.

* In the 1973 case of Roe vs. Wade, the Supreme Court held all state laws outlawing abortion were unconstitutional on grounds that the right of personal privacy extends to the right of a woman to decide to have an abortion.

Reagan has repeatedly said he supports a constitutional amendment banning abortion, and indicated he would sign any bill that comes to his desk that outlaws abortion.

In addition, the administration has moved vigorously to restrict abortions in other ways.

It has proposed eliminating federally financed abortions for rape and incest and has prohibited abortion coverage in the health plans of federal workers.

Reagan, during his first year, deliberately avoided any attachment to civil rights and so-called conservative issues because he did not want them to interfere with his economic and national security programs.

He also didn't want to create the impression he opposed equality or was a captive of the right wing among two groups critical to his election: Democrats, upset over the economy and the failures of big government, and moderate Republicans, who have traditionally supported civil rights measures.

But the accumulated actions of his administration now threaten Reagan's credibility among these groups. He is also facing mounting pressure from the political right to take a forceful role on abortion, school prayer and other social issues.

Those pressures put Reagan in a perplexing situation. His political roots are among conservatives, and he relied on their support during the 1980 primaries.

He shares their belief that the nation should be made "more like it used to be," before the reforms of the '60s and '70s. He shares their views on such issues as abortion and school prayer.

His pollster, Richard B. Wirthlin, has told him that "it is important in terms of consistency" that the president reiterate his views on these issues. But Wirthlin has also said these are "no-win issues" for Reagan and the Republican Party.

This calls for some tight-rope walking. Reagan has to say just enough about the issues to keep conservatives happy, but not so much that he alienates other Americans.

The abortion issue is a case in point. A Washington Post-ABC poll last spring found 74 percent of those surveyed support legalized abortion. Yet abortion is a litmus-test issue for many early Reagan supporters on the political right.

So the White House has kept the issue at arms length. Reagan, meanwhile, has communicated with conservatives through code words and symbols.

He didn't mention social issues in his State of the Union speech, for example, but he singled out one of their most outspoken proponents, Sen. Jeremiah Denton, as an American hero. His administration hasn't lobbied for anti-abortion legislation, but Reagan has invited anti-abortion leaders to the White House on two occasions.

Reagan has also made a series of symbolic appointments. Robert Billings, former executive director of the Moral Majority, was given a job in the Department of Education. Donald J. Devine, a former anti-abortion activist, became director of the Office of Personnel Management. He tried to eliminate abortion coverage in the health plans of federal workers.

Marjory Mecklenberg, another anti-abortion activist, became head of the population affairs division of the Department of Health and Human Services. She pushed through a proposal that would require parents to be informed when teen-agers under 18 get prescription birth-control products.

The greatest outcry over Reagan's appointees, however, has come from conservatives, who claim the president has ignored them. The current issue of Conservative Digest, a monthly published by New Right direct-mail expert Richard Viguerie, is devoted to accounts of how "non-Reaganites" have taken over the government.

Pressures on Reagan over conservative social issues are equally clear-cut. Unless the president takes an active role on the abortion issue, millions of fundamentalist Christians who supported him in 1980 may sit out the 1982 election, the Rev. Ron Godwin, vice president of the Moral Majority, said in an interview.

"Our people hold no loyalty to the Republican or Democratic Party. Rather they are interested in certain issues, and they are becoming increasingly frustrated," he said. "It would be the easiest thing in the world to keep them at home this fall. And if the religious right opts to stay out of the election, the Republican Party can expect a big disappointment."

There are equally compelling counterpressures. A common thread runs through the legislation dealing with the "big three" issues of abortion, busing and school prayer. All would strip authority from the federal courts.

This fits in with the administration's attack on judicial activism. But it has produced an outcry from constitutional lawyers, the American Civil Liberties Union, and even the staid old American Bar Association.

Here's where the issues stand:

Busing: The first skirmish in this year's social-issue war was fought over busing. On Feb. 4, the Senate, by a 58-to-38 vote, passed an amendment to the Justice Department authorization bill that would virtually end busing for the purpose of school integration. The measure would prohibit federal courts from ordering the busing of students more than five miles or 15 minutes from their home.

But the debate provided a glimpse at what to expect in the fight over other social issues. Opponents, led by Sen. Lowell P. Weicker Jr. (R-Conn.), argued the amendment was an assault on the Constitution and the separation of judicial and legislative powers.

They also claimed the social issues were irrelevant to the nation's real problems.

Said Weicker: "I suggest that to the rest of the country the real social issues are unemployment, high interest rates, and the bankruptcy of small businesses.

Abortion: Deep divisions within the anti-abortion movement are delaying action and may continue to do so. Two far-reaching anti-abortion measures were reported out of subcommittees last year.

One, sponsored by Jesse Helms (R-N.C.), the right's acknowledged leader on all the social issues in the Senate, would prohibit abortion by declaring that life begins at conception.

It is competing with a constitutional amendment sponsored by Sen. Orrin G. Hatch (R-Utah) and supported by Catholic leaders. The amendment would give Congress and the states joint authority to ban abortion. It declares no right to an abortion is secured by the Constitution.

Although his bill is on the Senate calendar, Helms said in an interview that he would not pursue it until anti-abortion groups "get their act together" and rally behind a single piece of legislation.

School prayer: The House last year passed a rider to the State, Justice, Commerce appropriations bill that would prevent the government from spending money to block any voluntary school prayer program--a largely meaningless move because the government has not been involved in such litigation anyway.

Weicker, who has vowed to block all the social issues, filibustered the bill, and it is still pending. Helms has introduced a tougher bill that would prevent federal courts from hearing voluntary school prayer cases.