Not Yet: Programs to Delay First Sex Among Teens is part of the National Campaign's "Putting What Works to Work" project, an effort to publish and disseminate the latest research on teen pregnancy in straightforward, easy-to-understand language and provide clear implications for policy, programs, and parents. It provides detailed descriptions of teen pregnancy prevention programme that have been shown through careful research to have delayed sexual initiation for teens. In additioná to providing results from program evaluations, Not Yet contains practical information on the costs and availability of program curriculum, and lengthy descriptions of what is covered in each curriculum. Not Yet joins the expanding base of program evaluation literature from which communities can draw in making their decisions about what programs they might consider using. Not Yet: Programs to Delay First Sex Among Teens begins with a summary of research on the consequences of early sexual initiation. This section is followed by an overview of the types of programs described in the report, along with a list of key insights that emerged from evaluations of the programs. Finally, the report profiles 15 programs that were evaluated using experimental designs (including programs that did and did not delay sexual initiation).