Understanding characteristics of teens' sexual relationships may help us to better understand how to reduce teens' risk of early unintended pregnancy and sexually transmitted diseases (STDs), as well as the psychological and emotional problems that may be associated with teenage romantic relationships and sexual activity. Using data from the National Longitudinal Study of Adolescent Health, this brief presents information that is relationship-specific because sexual experiences may be unique within different relationships. To increase the understanding of differences in sexual experiences among teens, the brief also examines relationship experiences, partner characteristics, and contraceptive use patterns separately by gender, race and ethnicity, age at first sex, and relationship type. These analyses have produced some important, and often troubling, findings. On the positive side, most teens consider their first sexual relationships to be more than casual flings: they view these relationships as romantic in nature. In addition, the majority of teens discuss contraception with their partner before they first have sex. On the negative side, an alarming proportion of teens experience some type of physical or verbal abuse within their first sexual relationships, they initiate sex very early in these relationships, and some teens never use contraception. An implication of the research presented in this brief is that parents, educators, and service providers who have a greater knowledge of adolescent relationship dynamics may be in a better position to help teenagers make more responsible decisions about sex and avoid many of the risks associated with it. (Contains 25 references and 9 figures.) (GCP)