I’m pleased that the focus of this issue of The Learning Professional is about measurement of professional learning. It’s important that professional learning leaders continue to find ways to document success and tie it to teacher excellence and student achievement. The subject matter is also personal to me because advocating for multiple measures of success was key to systemwide improvements we made in the California school district I oversaw. When I became superintendent of the San Mateo Union High School District in 2009, I shared with the board and key stakeholders that an investment in professional learning was key to student achievement — and that we’d have to find ways to measure success at key points along that journey. San Mateo is one of the