Female, Black, Latinx, Native American, low-income, and rural students remain underrepresented among computer science undergraduate degree recipients. Along with student, family, and secondary school characteristics, college organizational climate, curricula, and instructional practices shape undergraduates' experiences that foster persistence until graduation. Our quasi-experimental project, "Improving the Persistence and Success of Students from Underrepresented Populations in Computer Science" (I-PASS), is designed to augment students' persistence until they earn their computer science degree. Drawing on prior research, including Tinto's model of effective institutional actions for retention, I-PASS Scholars--all low-income, female and/or members of underserved demographics groups--receive a four-year scholarship; mentoring, tutoring, advising; and opportunities to integrate into the academic and social life of the campus. Students' written reflections and attitude surveys suggest I-PASS's components foster their retention by, among other mechanisms, enhancing their computer science identity development and sense of belonging in the major.