The results of this search, although by no means exhaustive, produced 55 books, papers, and articles that included some efforts to connect learning communities with teaching practice and/or student achievement. In selecting material for this literature review, we decided to limit the review to published articles or book chapters that included data about the impact of school-based PLCs on teaching practice and/or student learning. Using these parameters the search provided only 10 empirical studies of the work of teachers in learning communities. In addition, we decided to include one large multi-site research report commissioned and published by the General Teaching Council of England, Department for Education and Skills.