Teacher education and professional development prepare teachers with up-to-date knowledge, skills, and dispositions necessary for effective teaching. To sustain this, however, hinges on continued professional learning within schools. Research shows that establishing long-term conditions that allow teachers to learn continuously from one another within schools is among the most effective ways to support teacher learning (Heck, Banilower, Weiss, & Rosenberg, 2008). At a private school in metropolitan New York City, eight pre-K through 8th-grade teachers have the chance to do just that by participating in monthly professional learning focused on improving math instruction. The program engages multilevel teacher groups in three steps: brief, observe, and debrief. Using this framework, the school supports teacher learning about reform-based instructional practices, including content development across grade levels.