In this dissertation, I study the relationships between financial aid, student characteristics, persistence, and completion in three separate chapters. In all three chapters, I use detailed, student-level administrative data from the UNC System beginning in the Fall 2013 semester. The first chapter is entitled "Tuition Reduction and Student Loan Debt: Effects of the North Carolina Promise." I analyze the impact of a state policy, the NC Promise Tuition Plan, that lowered the sticker price of college tuition at three four-year institutions in North Carolina. This unique policy, which falls under the broad umbrella of 'promise programs', is rare in the four-year context. NC Promise decreased fall and spring semester tuition to $500 for in-state students at three public institutions in North Carolina for all new and continuing students beginning in the Fall 2018 semester. Prior work on this financial aid program suggests it had little effect on first-time enrollments, but increased transfer enrollment at two of the three institutions (Klasik et al., 2022). Using difference-in-difference methods and student-level financial aid information, I contribute to the literature by estimating the causal effect of NC Promise's tuition reduction on student loan decisions. In the next chapter, entitled "Adult Learners: Financial Aid and College Success for Veterans, Parents, and Post-Traditional Students," I explore persistence and completion related to student-level factors and financial aid for adults, veterans, and student parents in North Carolina. Historically, adult students have been treated as a monolith of college students over the age of 24 and few researchers have focused their work specifically on adult students in the four-year context. As a result, much of the research on adult students focuses on the community college context, and policy and policymakers rarely consider these students at four-year universities. Similarly, financial aid also tends to target first-time student enrolling directly after high school. In this study, I contribute to the literature by using a sophisticated descriptive approach to explore the persistence and completion rates adult students, veterans, and parents. In the final chapter, entitled "Exit, Re-Enrollment, and Completion in the University of North Carolina System," my research questions focus on stop-out, re-enrollment, and completion across three cohorts of students. This work follows up the previous chapters by further exploring persistence and completion for another population of students: stop-outs. While there is an extensive literature on student dropout, we know less about persistence and completion for students who pause enrollment. These students are categorically unique in that they do not continue through college in consecutive semesters like the majority of students. In this study, I make several contributions to the literature on understanding stop-out, re-enrollment, and completion. First, it contributes a needed description of the trajectory of stop-outs and re-enrollees in a large public university system over a long period of time while considering multiple stop-outs across multiple institutions. Second, it is one of few studies to investigate the persistence and completion among students who re-enroll after dropping out using statewide data. [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.]