 Prevention scientists have rigorously tested programs and policies that address these risk and protective factors in studies funded largely by the National Institutes of Health, and an increasing number and range of effective prevention approaches have now been identified.By 2004, 56 tested and effective programs were available in the United States that have been demonstrated to reduce involvement in problem behaviors and/or increase positive outcomes for youth.These 56 effective programs and policies are summarized in CTC's Prevention Strategies Guide at https