Presents results from a 15-city National BEST (Building Exemplary Systems for Training Youth Workers) Initiative, the primary goal of which is to increase training and education resources for youth workers in local communities. The report highlights changes in youth development practices after workers participated in a variety of training opportunities, including programs based on the Advancing Youth Development (AYD) curriculum. Among the major conclusions of the study is that youth workers who complete AYD are better practitioners of the youth development approach, as demonstrated by such practice changes as: involving youth as planners and leaders, concentrating more on helping adolescents develop specific competencies, and collaborating with other youth-serving organizations to exchange information and resources to benefit young people in their programs. The BEST Initiative is effective as both a strategy and model for building a system of professional development services and supports to young workers. Effective youth workers are individuals who: (1) participate in ongoing professional development as well as in strong networks for information sharing; and (2) have the support of their organizations to implement quality programming. An important area for further research is the impact of the BEST Initiative model on recruitment and retention patterns of youth workers.