One of the most fundamental human needs and motivations is that of forming and maintaining social connections with others (see Baumeister & Leary, 1995). This need for belongingness may be even more important for individuals going through stressful transitions in their lives. The high-school to college transition is a stressor that challenges students’ sense of belonging. Additionally, there may be individuals (e.g., underrepresented minority students, international students) who are particularly vulnerable to the high-school to college transition and COVID-19 stressors. The current dissertation examines a field-study belonging intervention that focuses on increasing students’ sense of belongingness in their first year (Walton & Cohen, 2007). Students completing a belonging intervention are compared to students who do not receive this manipulation in terms of their sense of belonging across two time points during their first year. Furthermore, this dissertation extends previous research on belonging interventions by examining mechanisms of social integration and social networks. This research has theoretical implications for understanding the mechanisms underlying belonging interventions as well as practical implications for the application and efficacy of a belonging intervention.