An ad hoc committee will plan and convene a workshop to inform the National Science Foundation’s Directorate on Education and Human Resources in its mandate to help prepare a broad and diverse U.S. Science, Technology, Engineering, and Mathematics (STEM) workforce for the 21st century. The activity will contribute to NSF-EHR’s preparation of a theoretical and evidence-based STEM Workforce Development R&D Core Framework. Workshop participants will suggest refinements in the goals for the framework, discuss research themes, and identify gaps as well as emerging research opportunities related to STEM workforce development. Possible themes for discussion include STEM pathways and transition points, STEM teaching and learning, career preparation and interdisciplinary education and training. An individually-authored workshop summary will be prepared by a designated rapporteur in accordance with institutional guidelines. The workshop and summary will also serve as resources to federal and state policymakers, researchers, employers, and foundations that are contributing to the development of a robust and diverse U.S. STEM workforce.