Youth service professionals in various settings across the United States are responsible for preparing youth and youth adults, ages 12 to 25, to be successful in employment, postsecondary education, and adult life. Whether they work in the public workforce development system or other public agencies (e.g., child welfare, juvenile justice, mental health, health, disability services), in schools or postsecondary institutions, or for nonprofit organizations, they are often the "face" of their organizations. Young people frequently base their decisions about whether or not to engage with an organization on their relationship with one or more youth service professional. As a result, much rests upon their level of competence in connecting with and assisting youth through a critical period of their development. This Info Brief describes strategies and considerations for designing and delivering professional development for youth service professionals at the state and local levels. By highlighting strategies, required resources, and lessons learned from three different professional development initiatives, this brief aims to inform the decisions of organizations, agencies, and funders as they consider how to invest in professional development efforts within the workforce development system as well as other youth service systems and program contexts.