These organizations were selected because they aim to draw youth solely by the appeal of their environments and activities, provide building blocks to healthy adult functioning, are sufficiently diverse to provide lessons for other organizations, and have strong youth participation and volunteer support. Issues addressed in the study were whether the groups' settings attract a diverse group of youth, whether youth spend enough time in these environments for them to provide significant experiences, and the types of positive structured and unstructured activities that attract youth in these settings. A fourth issue addressed was whether measures could be developed and used to document the developmental supports and opportunities critical to making a healthy transition to adulthood. Seven developmental supports and opportunities were identified and measured: a sense of safety, challenging and interesting activities, a sense of belonging, social support from adults, input and decision-making, leadership, and volunteer and community service. The general methodology used included tracking attendance and activities at sites, a survey of adolescents' experiences, and conducting site visits to collect data on organizational structure and practices. The findings produced two general conclusions. First, there is a feasible method for assessing the effectiveness of organizations implementing a youth development approach. Second, when a youth development approach is undertaken, it can both attract and hold the interest of adolescents and can become an effective means for achieving developmental goals for a wide variety of youth without focusing on deficits or problems. 24 tables, 1 figure, and appended supplementary material