This guidebook explores some of the practical issues associated with finding, choosing, and starting potentially effective prevention programs for at-risk preteens and teens. The guidebook is based on a study of 51 intervention programs that identified elements and delivery mechanisms that were associated with their effectiveness. A closer look at a subset of 21 programs provided more information about program strengths. This booklet contains an update on adolescent risk taking and explains why it is necessary to improve and expand the network of effective prevention programs for at-risk teens. The common elements of the successful programs are described, results of program evaluations are summarized, and general and contact information are given. The challenges facing practitioners seeking to replicate promising intervention programs or approaches are discussed. A prevention readiness questionnaire is provided to help program directors and planners identify and assess factors necessary to create favorable conditions and circumstances for successful adaptation or replication of the programs. Profiles of 51 programs show the reasons they are successful. A reference chart is included to enable quick comparison of the programs. (Contains 35 references.) (SLD)