Evidence on what works for whom in the field of teen pregnancy prevention would help program developers design more effective programs and help practitioners select and implement programs most appropriate for their local populations. A new meta-analysis led by Abt Global and Vanderbilt University used data from 44 federally funded impact evaluations of teen pregnancy prevention programs to investigate whether the short-term effects of these programs on sexual behavior and pregnancy were associated with program or participant characteristics. The study’s findings suggest that girls-only programs and programs utilizing individualized service delivery might be more effective than other types of programs. These findings suggest the need to reexamine assumptions about coed group approaches.