Many departments seek to improve their equity, diversity, and inclusion using data-informed methods; however, not much is known about how closely department leadership aligns their review practices with appropriate theory. This dissertation seeks to explore four areas: 1) how are equity, diversity, and inclusion are being conceptualized (implied theory of change), 2) how are equity, diversity, and inclusion being operationalized (implied theory of action), 3) what process is each department going through to evaluate equity, diversity, and inclusion (implied theory of evaluation), and 4) how are data interpreted and used, or not used (implied philosophy of change). This study investigates how theory undergirds department action by using two exploratory case studies--two departmental EDI teams within the School of Medicine--with a cross case analysis. Findings show a loose theory of change was provided at the school level for both departments, but departments lacked concrete definitions of equity, diversity, and inclusion that connected to this theory of change. Departments generated many theories of change and action that varied greatly and did not cohesively align with their interventions and review process. They tried to include various voices in the evaluation process, but could benefit from having a more robust understanding and implementation of culturally responsive, equity-focused evaluation. The departments had an accountability framework levied on them by the School of Medicine, which had showed promise at a previous school, but there was debate about the role of incentives in catalyzing change. Overall, departments would do well to reflect on their philosophy of change when designing and evaluating their programs. Although they included many voices in the evaluation process, the departments could do more to consider the least well-off groups, especially because anti-affirmative action legislation like Proposition 209 prohibits favoring based on attributes like race and gender. Once departments have results back, they should consider how to target their change efforts by choosing a philosophy of change approach. With a theory of change, theory of action, evaluation theory, and theory of change all articulated and aligned, a department will have a much better probability of enacting real change in equity, diversity, and inclusion. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]