This report reviews the research literature on professional learning communities (PLCs) in order to provide insights into of how practice-based research, in the form of various types of collaborative inquiry, could be promoted in ways that improve teaching and learning in Swedish schools. The review is based on research from many parts of the world, published in peer reviewed English-speaking journals and books. It thus has relevance beyond the Swedish context as well. The report presents research findings demonstrating the benefits of PLCs. It also describes the defining characteristics of these PLCs. Finally, it provides a research informed discussion of how PLCs could be developed and sustained, including suggestions that can inform future research. The report thus offers several important insights that can prove valuable to both researchers and policy makers seeking ways to develop teaching and learning in primary and secondary schools.