This Yearbook chapter, a compilation of multiple sources, presents both the history of action research and an analysis of reported action research in the professional development school (PDS) between 1992 and 2010. The history begins prior to the inception of the PDS and provides a theoretical premise for action research in the PDS in subsequent years. Sixtyfour action research PDS articles used to develop the chapter, derived from EBSCOhost searches, resulted in 38, or 59%, of the articles from ERIC databases. The remaining 26 articles, or 41%, were published in refereed and nonrefereed journals. The 33 other sources used for the chapter consisted of books, chapters in books, reports, Web pages, and monographs from agencies. The chapter represents an in-depth study of action research in the PDS with recommendations for future practice and collaboration.According to the Center for Collaborative Action Research (2010), action research is defined as a process of deep inquiry into one's practices in service of moving towards an envisioned future, aligned with values. Action Research is the systematic, reflective study of one's actions, and the effects of these actions, in a workplace context. As such, it involves deep inquiry into one's professional practice. The researchers examine their work and seek opportunities for