This publication provides an overview of the types of professional development available in the out-of-school time field, outcomes participants or organizations can expect related to each type of professional development opportunity, principles of effective professional development for trainers, managers, and front-line staff, and considerations individuals and/or organizations must make when deciding on deploying resources for professional development. These include decisions related to cost and investment, learning-readiness, assessing staff needs and interests, creating incentives, and assessing impact.