THIS year marks the twentieth anniversary of the National Opinion Research Center's General Social Surveys, a remarkable barometer of the social attitudes and behavior of the American people. Of course attitudes on some issues have changed during the two decades from President Nixon's reelection, through Watergate, the Carter years, and the Reagan Revolution, but the dominant theme is continuity.Since 1972 the frequency of attendance at religious services has declined slightly, but the change has been minimal. Rising support for euthanasia reflects the growth of a secular definition of sympathy for the dying in the face of an aging population and the availability of extraordinary medical intervention. Not surprisingly, the growing concern about crime has brought about a significant increase in support for two symbolic remedies, the death penalty and gun control. But on many social issues change has been less evident. Although some sexual attitudes (about, for instance, premarital sex) continued to evolve during the 1970s, the past decade was one of stabilization. On other issues, like the morality of homosexual relations, the sexual revolution seems to have had little affect. Attitudes about abortion have changed very little. The long-standing public ambivalence, which values a woman's control over her own body yet rejects frivolous use of abortion, persists. Since 1974 there has been some toughening of attitudes about divorce, but the long-term trend is unclear. The last decade and a half witnessed a sharp decline in smoking, but alcohol use (as measured by the percentage of people who occasionally drink) has remained relatively constant.