In this report, we identify studies that link coaching and specific coaching models with outcomes for classrooms, providers, and children, while also highlighting critical aspects of coaching. Specifically, we summarize the research base for coaching as a professional development tool, including the strengths and weaknesses of this research. In the appendix tables, we provide considerable detail to support the summary information in the body of the report. We begin by briefly describing the process of the literature review, including its sources of information. In an earlier memorandum, we provided details on the framework for this review (Aikens et al. 2011).