Objectives/Goals: This study’s objective was to explore how a personal cancer diagnosis impacts the social connectedness (i.e., quality, structure, and functions of social relationships) of adolescent/young adult cancer survivors (AYACS, patients diagnosed with cancer between 15 and 39 years old), to inform intervention development fostering social health. Methods/Study Population: In this qualitative study (part of larger study assessing AYACS’ psychosocial challenges), participants were 15–25 years old at the time of cancer diagnosis and within 6 years of cancer diagnosis. Participants (and consenting parents of participants 18 years old and older) had to have fluency in written and spoken English and access to a computer or smartphone. Qualitative interviewers utilized an interview guide to conduct individual participant interviews. Interviews were audio-recorded and transcribed verbatim. Thematic analysis was used to analyze data using a phenomenological approach to explore how a personal cancer diagnosis impacted social connectedness. Qualitative data related to social connectedness (corresponding to code “Relationships and Support”) are presented. Results/Anticipated Results: Three themes emerged through thematic analysis: (1) AYACS experience substantial heterogeneity related to social support needs; (2) AYACS leverage multiple relationships and resources when seeking support after a personal cancer diagnosis; (3) AYACS’ individual experiences were unique in that some noted positive changes, whereas others noted negative changes in relationships within social networks, specifically with peers. Discussion/Significance of Impact: AYACS experience various social support needs, and leverage multiple relationships when seeking social support. These translational findings create a foundation to develop AYACS social programming, foster peer relationships, and incorporate social science methods to aid intervention development to strengthen AYACS’ social connectedness.