The purpose of this article is studying how leaders learn to cultivate mathematically rich professional development environments. The authors adapted two frameworks from classroom-based research to support leaders’ understanding of facilitation of mathematics professional development: sociomathematical norms and practices for orchestrating productive discussion. They describe the use of these frameworks in their work and argue for a third framework—the mathematical knowledge for teaching. 24 NW leaders and 12 SW leaders participated in the seminars developed by the authors.