The proportion of U.S. women who used a contraceptive method at their first premarital intercourse rose from 47 percent in 1975-1979 to 65 percent in 1983-1988. Overall, and among non-Hispanic white women, this change resulted entirely from an increase in the use of condoms by their partners. The proportion of whites who used a condom at first premarital intercourse, for example, increased from 24 percent to 45 percent. Among blacks, condom use at first intercourse increased from 24 percent to 32 percent during that period, and pill use rose from 15 percent to 23 percent. Among all women, the method most often used at first intercourse during every period in the study was the condom, followed by the pill and withdrawal. The proportion of women using a method at first premarital intercourse varies strikingly according to individual characteristics. Among the various demographic subgroups, the proportion who use a method varies from 32 percent of Hispanic women to 68 percent of Jewish women. Whites are more likely to use a method than are blacks, and fundamentalist Prostestants are less likely to use a method than are other Protestants or Catholics. The proportion using a method is higher among women whose mothers completed high school than among those whose mothers did not. In addition, the proportion rises with age at first intercourse. Multiple logistic regression showed that the independent effects of Hispanic origin, Jewish or fundamentalist Protestant religious affiliation and the education of a woman's mother are large and significant.(ABSTRACT TRUNCATED AT 250 WORDS)