A new Government Accountability Office report and U.S. Department of Education guidance elevate teacher collaboration as a promising strategy for professional development tied to student learning. The GAO analysis found that more than two-thirds of public K-12 teachers view educator collaboration as the “most useful” element of PD, and collaboration showed stronger associations with improved student test scores than some other PD formats. The Education Department’s February guidance encourages districts to use Title II funds—$2.2 billion annually for teacher professional development—to support team teaching and other staffing models that increase opportunities for high-performing teachers to share expertise. The update arrives as the administration proposes changes that could eliminate Title II grants or consolidate funding into a block-grant structure, raising uncertainty about whether districts can sustain collaborative PD models at scale.