• We tested the hypothesis that the nature of the heterosexual relationship would be associated with the contraceptive and sexual behavior among three groups of females: those with a boyfriend who agreed to be interviewed (n=31); those whose boyfriends refused to be interviewed (n=38); and those without a single identifiable boyfriend (n 44). A pretested questionnaire was administered to a random sample of 113 black females aged 12 to 18 years from a lower socioeconomic population. The three groups did not differ in age, Tanner stage, previous pregnancies, or in demographic variables. Females with boyfriends were more likely than others to be currently sexually active. Overall, 47.8% of the sample was sexually active. Females whose boyfriends were interviewed were more likely to feel that having a baby would ruin their life. Among sexually active females (n = 54), a higher percentage of females whose boyfriends were interviewed (90%) were currently using a prescription method of birth control and demonstrated higher previous contraceptive compliance. There were no differences between the groups with boyfriends in the degree that the females felt their boyfriends supported their use of birth control; those without boyfriends perceived less support. Six months after the initial interview, a higher percentage of sexually active females had a boyfriend as compared with other subjects. Although the 31 females and their boyfriends differed in the mean scores of several sexual behavior and attitude scales, the girls' and their boyfriends' scores on these scales were moderately correlated. These findings suggest that the nature of the heterosexual relationship may influence both the sexual and the contraceptive behavior of black female adolescents.