Researchers and practitioners continue to call for professional learning (PL) for multi-tiered systems of support (MTSS) to promote implementation with fidelity. Different PL interventions and MTSS frameworks raise questions about what types of PL support educators to engage in key practices. Questions also remain regarding educators' perspectives and experiences with PL for MTSS and factors that facilitate or hinder educators' learning. In this paper, we report findings from a qualitative research synthesis on PL for MTSS in the United States. We found 46 studies that explored educators' perspectives and experiences with PL. Findings illuminated educators' positive experiences with ongoing, job-embedded PL, particularly PL communities and coaching. Studies also illustrated the importance of collaboration and trust within learning communities as well as leaders who empower and trust educators. We discuss the implications of these findings in K-12 school settings.