Dissertations are considered an important part of the grey space of academic literature given that they are controlled by university faculty, not by commercial publishers. Study of doctoral dissertations provides an indication of the latest innovations and research interests of the newest generation of researchers and practitioners. Examination of dissertation research typically conveys the influence of contemporary training standards and the state-of-the-art research methodologies. Systematically investigating the grey space of professional development school dissertation research can offer insight into general PDS trends studied by emerging scholars. This study explores the grey space to identify trends from three decades of professional development school dissertation scholarship. The overarching research question for this study was, ''What can we learn from the examination of doctoral dissertations that focus on professional development schools from 1990 through 2020?'' To date, there has been no comprehensive analysis of the descriptive and conceptual characteristics of the PDS dissertation literature. As the PDS movement completes a third decade of inquiry, analyzing the corpus of PDS dissertation research might offer insight into what doctoral students and their advisors have regarded as important to the field across the last three decades. The findings can provide insight into the nature of the work accomplished and the degree to which PDS scholars are building on the past to determine future PDS research agendas and raise questions regarding PDS work moving forward.