Between-school segregation poses significant challenges for students’ short- and long-term success as well as for societal cohesion. Diversifying schools with regard to students’ background characteristics is theorized by scholars from multiple disciplinary perspectives as an important social and policy endeavor. However, it can be an uphill battle due to several barriers, including residential segregation, inequitable distribution of school options, social closure dynamics, information asymmetries, and others. In my dissertation, I conduct applied quantitative analyses that speak to the potential benefits of and policy avenues toward more diverse school contexts. While the two quantitative chapters use different data sources and explore different questions, (i) they align broadly under the umbrella of the literature on between-school segregation and school diversity; (ii) they both are interdisciplinary analyses, bringing together knowledge from sociology and economics; and (iii) they both employ causal frameworks, exploiting exogenous variation derived from cross-sectional policy shocks and longitudinal demographic changes. To begin the dissertation, in Chapter 1, I review the theoretical and empirical literature on school-based segregation and diversity, arguing that key components of the theory have not yet been fully tested empirically. Chapter 2 investigates the effects of school-based segregation and—on the flipside—school-based student diversity on short-term academic outcomes. I document changes in school racial and ethnic composition over time using statewide data from Maryland. Then, I assess the causal effects of these changes on short-term test scores and suspensions, using a value-added and a student-school fixed-effects approach. I find that, while most students benefit from being enrolled with a larger proportion of students of color, the association is non-linear and heterogenous by the student’s race-ethnicity. The findings suggest that policy discussions around school diversity need to consider how potential shifts in peer composition may dissimilarly impact different students and institutional dynamics in more/less diverse schools at baseline. Chapter 3 examines the effects of a policy in Chile that prohibits selective admissions and introduces a centralized admissions lottery as a possible policy solution to between-school segregation in school choice contexts. Relying on publicly available administrative data, I exploit rollouts across regions and municipalities for identification in a difference-in-differences and event study framework. I find that prohibiting selective admissions reduces between-school socioeconomic segregation, mitigating the stratifying effects of school choice. The findings suggest that specific regulations are central for school choice systems to achieve their theorized goal of expanding schooling alternatives by breaking the link between neighborhood and segregative district boundaries. By drawing upon the findings of both papers, the dissertation highlights the normative and empirical complexities that the analysis of school segregation and diversity entails for policy and research aimed at attaining a more equitable distribution of educational opportunities.