OBJECTIVE To describe the characteristics of several types of sexual partners of African-American and Hispanic urban youth and to determine the association of these characteristics with condom use, contraceptive use, experience with sexually transmitted diseases, and sexual practices. METHODS Data were drawn from personal interviews with a probability sample of low-income urban youth, age 15 to 24 years, conducted in Detroit in 1991 (N = 1,435). RESULTS Although both ethnic groups tended to form partnerships most often within their own group. Hispanics had sexual partners who varied by ethnicity much more than did African Americans. Furthermore, the longer-term relationships, those that resulted in marriage or cohabitation, were more likely to be with Hispanic partners than were other relationships. Hispanic men were also more likely to report white partners than were Hispanic women. In contrast, for African-American men and women, most reported relationships were with other African Americans. Regardless of ethnicity or relationship type, women had older partners than did men. Partner differences in age or ethnicity showed few or no differences in condom use, reports of sexually transmitted disease, oral intercourse, or use of contraceptive methods. CONCLUSIONS Although relationships with people of similar age and ethnicity are common, bridges exist for transmission of sexually transmitted infection between different age and ethnic groups.