This collection of papers on early adolescent sexual behavior includes seven papers in two parts. Part 1, "Papers from Nationally Representative Data Sets," includes (1) "Dating and Sexual Experiences among Middle School Youth: Analyses of the NLSY97" (Elizabeth Terry-Humen and Jennifer Manlove); "(2) "Dating Behavior and Sexual Activity of Young Adolescents: Analyses of the National Longitudinal Study of Adolescent Health" (Hannah Bruckner and Peter Bearman); and (3) "Sexual Activity among Girls Under Age 15: Findings from the National Survey of Family Growth" (Christine M. Flanigan). Part 2, "Papers from Small Area Data Sets," includes (4) "The Development of Sex-Related Knowledge, Attitudes, Perceived Norms, and Behaviors in a Longitudinal Cohort of Middle School Children" (Cynthia A. Gomez, Karin K. Coyle, Steve Gregorich, Barbara VanOss Marin, and Douglas B. Kirby); (5) "Youth with Older Boyfriends and Girlfriends: Associations with Sexual Risk" (Barbara VanOss Marin, Douglas B. Kirby, Esther S. Hudes, Cynthia A. Gomez, and Karin K. Coyle); (6) "Community Concerns and Communication among Young Teens and Their Parents: Data from California Communities" (Susan Philliber); and (7) "Sexual Behavior among Young Teens in Disadvantaged Areas of Seven Cities" (Susan Philliber and Michael Carrera). The data come from surveying 12-, 13- and 14-year-olds as one group; surveying a group of 12-year-olds and then following them over time as they turned 13 and 14; and surveying older teens about their experiences when age 14 and younger. Among the findings of the studies: nearly one in five adolescents has had sex before his or her 15th birthday; contraceptive use among young adolescents is relatively low; and sexually experienced youth age 14 and younger are much more likely to smoke, use drugs and alcohol, and participate in delinquent activities than youth who have not had sex.(Papers contain references.) (SM)