This study explores the role of community characteristics in determining two critical features of adolescent nonmarital sexual activity: the timing of first intercourse and contraceptive use at that event We specify a conceptual model describing the mechanisms by which the community context affects adolescent behaviors, focusing on the influence of community social and economic characteristics on teenagers' expectations about their adult lives. We test hypotheses derived from this model using a multilevel strategy incorporating both aggregate- and individual-level data for a national sample of white women. The results suggest that the behaviors of adolescents are shaped by the local opportunity structure and normative environment. Social disintegration, socioeconomic status, and the availability of employment opportunities for women emerged as particularly important influences on young women's reproductive choices.