The first volume of this SpringerBrief presents a series of papers compiled from a conference about how after-school programs may be implemented to promote positive youth development (PYD) hosted by Youth-Nex, the University of Virginia Center to Promote Effective Youth Development. This volume reviews the importance of after-school programs for PYD and discusses key components of effective after-school programs. It also discusses issues related to the evaluation and measurement of quality in after-school programs. In addition, the brief presents suggestions for how researchers, policy makers, and practitioners can move the field forward and maximize the potential of after-school time and programs for promoting positive youth development for children and adolescents.  Topics featured in this brief include:  The history of the relationship between after-school programs and positive youth development.  Specific features of programs that are important for advancing positive youth development.  Issues in and approaches to measuring quality in after-school programs. The Quality, Engagement, Skills, Transfer (QuEST) model and its use for measuring effective after-school programs.  A case study evaluation of the Girls on the Run program.  After-School Programs to Promote Positive Youth Development, Volume 1, is a must-have resource for policy makers and related professionals, graduate students, and researchers in child and school psychology, family studies, public health, social work, law/criminal justice, and sociology. .