The Girl's health Enrichment Multi-site Studies (GEMS) is a collection of studies designed to develop and test interventions to prevent excessive weight gain by African-American girls as they enter and proceed through puberty. The research is being conducted as four inter-dependent, clinical trials. They are "inter-dependent" in the sense that they are considering similar study populations, following similar follow-up schedules and use a "core" set of evaluation procedures. Nonetheless, GEMS is not a "multi-center clinical trial" in the usual sense - each field center is evaluating its own intervention (and corresponding control). As a result, each study will have high internal validity and will be designed and analyzed as a study in its own right.