Quality program implementation is critical for obtaining intended outcomes and thus required the attention of practitioners, researchers, and policymakers. This brief defines program implementation, highlights the importance of a high quality implementation, identifies key factors that affect implementation, discusses steps in achieving quality implementation, and specifies who has responsibility for quality implementation. Understanding how implementation should be considered in the adaptation of evidence-based programs is considered and some practical lessons learned about implementation through systematic research and practice are shared. Throughout this brief, the terms program and intervention are used interchangeably to refer to a planned set of activities that are being introduced into a new setting to assist youth and their families in various ways.