Since its creation in 2014, the Instructional Leadership Corps, a peer-based professional development project involving the California Teachers Association, the National Board Resource Center and the Stanford Center for Opportunity Policy in Education, has provided multi-session trainings in the Common Core and Next Generation Science Standards. An examination of four instructional teams, at Madera Unified, Conejo Valley Unified, the East Side Alliance in San Jose and a network of Orange County teacher leaders and CSU Fullerton, found that teachers valued professional learning led by their colleagues, and teacher leaders broadened their sense of professional effectiveness.