This dissertation is motivated by a need in the higher education learning sciences field to understand the cultural, social, and emotional processes of student learning and development in advancing equity for students from first-generation, low-income, and marginalized backgrounds. To address this need, I develop and examine a sociocultural conceptual framework called the zone of proximal self. The zone of proximal self is the distance between a learner's current self and their possible selves which can be bridged through support from institutional figures, resources, and materials across a broad learning ecology in higher education. The structure of this dissertation paper includes the three papers followed by an integrated discussion in the conclusion. In a series of three papers, I use the zone of proximal self as a lens to study college students' interactions in postsecondary settings during the COVID-19 pandemic. In my first paper, I use mixed methods approaches to analyze survey results from 524 students at a private four-year university to explore first-generation students' experiences with institutional resources. In my second and third paper, I draw on a study of 50 students at a public four-year university who were asked to meet with a counselor or advisor throughout an academic term and share their experiences through diary entries, surveys, and an interview across a 14-week semester. Results from the first paper reveal how barriers persist for students in interacting with institutional resources; and it reveals the importance of shifting the focus from the role of student meritocracy to that of institutional structures and variability in access to interpersonal and material resources. The second and third paper highlight three pillars of effective practices from counselors and advisors -- creating a brave space, validating students, and supporting students' social-emotional competencies -- which are associated with higher growth in students' professional and personal goals for their possible selves. Taken together, a zone of proximal self lens illuminates how advancing equity in higher education will require humanizing notions of college student success beyond a narrow focus on academic outcomes. The findings which surfaced from an "interpersonal plane of analysis" (Rogoff, 2003) offer design implications for formal and informal learning environments in higher education to incorporate dimensions of humanizing relational practices between students and institutional figures and resources. Moving forward, this work opens up new lines of research to better theorize and assess how humanizing relational practices emerge and foster growth in the zone of proximal self for students from first-generation, low-income, and marginalized backgrounds. [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.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]