We describe the process and outcomes of a project aimed at bringing together a set of diverse experts to generate a set of design recommendations for what should be considered when creating, sustaining, and assessing professional development systems to support the Common Core State Standards in mathematics. Although the recommendations were generated in mathematics, the underlying guiding principles for professional development are generalizable to other disciplines. As such, we discuss implications for professional development more broadly. (Contains 1 note and 1 figure.)