Until recently, teen pregnancy and birth rates had declined steadily in the United States in recent years. Despite these declines, the United States has the highest teen birth rate and one of the highest rates of sexually transmitted infections (STIs) among all industrialized nations. To help young people reduce their risk for pregnancy and STIs, including HIV, program planners should look to the body of available evaluation and research to identify effective programs. To this end, Advocates for Youth established a set of stringent criteria for determining program effectiveness. Staff then conducted an exhaustive literature review. This paper describes 26 programs that meet the rigorous criteria. Nineteen programs appeared in "Science and Success" when it was first published in 2003; seven additional programs are included in "Science and Success, Second Edition." [This document was prepared with assistance from Emily Bridges, Tanya Gonzalez, Laura Davis, and Debra Hauser.]