More than 1 million teenage girls in the United States become pregnant each year; nearly half give birth. Why do these young people, who are hardly more than children themselves, become parents? This volume reviews in detail the trends in and consequences of teenage sexual behavior and offers thoughtful insights on the issues of sexual initiation, contraception, pregnancy, abortion, adoption, and the well-being of adolescent families. It provides a systematic assessment of the impact of various programmatic approaches, both preventive and ameliorative, in light of the growing scientific understanding of the topic.