Highlights• Deepen and refine our understanding of workforce development across multiple settings and sectors • Provide a conceptual model of interactive ecological factors that influence professional development • Suggest a framework for further scholarship on workforce best practices in low-resource communities Abstract The professionals and paraprofessionals who work daily with youth in low-resource, marginalized communities are integral to youth wellbeing; yet, their professional development, and the factors that promote it, are not well understood. In this introduction to the special issue, Understanding and Strengthening the Child-and Youth-Serving Workforce in Low-Resource Communities, we focus on understudied practitioners operating in an array of sectors and settings, such as home visitors, mental health paraprofessionals, early childhood assistant teachers, teachers in low-income countries, school resource officers, juvenile justice staff, and after-school and community-based program workers. We put forward a conceptual model detailing the interactive, layered set of proximal-to-distal ecological factors that influence the practice and professional development of these workers, and show how papers in the current issue address these layers in their examination of workforce development. We conclude with a summary of the contributions and lessons from this workincluding the value of a whole-person approach, the importance of sharing process across research stages, and the need to build on the foundation provided by community psychology and implementation sciencetoward the twin goals of understanding and building the skills and strengths of the workforce, and ultimately, enhancing youth development.Keywords Professional development Child and youth well-being Evidence-based practice Implementation science Ecological systems theory Both authors contributed equally in the writing of the current manuscript and are listed in alphabetical order.