Book excerpt: This report summarizes three bodies of research on teenage pregnancy and programs to reduce the risk of teenage pregnancy. Studies included in this report were completed in 1980 or later, conducted in the United States or Canada, targeted adolescents, employed an experimental or quasi-experimental design, had a sample size of at least 100 in the combined treatment and control group, and measured the impact on sexual or contraceptive behavior, pregnancy, or childbearing. Six chapters focus on: (1) "Making the Case for Prevention Efforts: Adolescent Risk-Taking Behavior and Its Consequences"; (2) "Looking for Reasons Why: The Antecedents of Adolescent Sexual Behavior"; (3) "Assessing the Evidence: Factors Affecting the Strength of Research Results"; (4) "Emerging Answers: The Behavioral Impact of Programs To Reduce Adolescent Sexual Risk-Taking"; (5) "Looking Forward: Conclusions about the State of Research and the Effectiveness of Programs"; and (6) "Bringing It Home: Applying These Research Results in Communities." (Chapters contain references.) (SM)