The aim of the study was to characterize perceived social support for young men and transgender women who have sex with men (YM/TWSM) taking HIV pre-exposure prophylaxis (PrEP). METHODS: Mixed-methods study of HIV-negative YM/TWSM of color prescribed oral PrEP. Participants completed egocentric network inventories characterizing their social support networks and identifying PrEP adherence support figures. A subset (n = 31) completed semistructured interviews exploring adherence support and qualities of PrEP support figures. We calculated proportions of role types (e.g., family), individuals disclosed to regarding PrEP use, and PrEP-supportive individuals within each participant network. Interviews were analyzed using an inductive approach. RESULTS: Participants (n = 50) were predominately African American men who have sex with men. Median age was 22 years (interquartile range: 20-23). Biologic family were the most common support figures, reported by 75% of participants (mean family proportion .37 [standard deviation (SD): .31]), followed by 67% reporting friends (mean friend proportion .38 [SD: .36]). Most network members were aware (mean disclosed proportion .74 [SD: .31]) and supportive (mean supportive proportion .87 [SD: .28]) of the participants' PrEP use. Nearly all (98%) participants identified ≥1 figure who provided adherence support; more often friends (48%) than family (36%). Participants characterized support as instrumental (e.g., transportation); emotional (e.g., affection); and social interaction (e.g., taking medication together). Key characteristics of PrEP support figures included closeness, dependability, and homophily (alikeness) with respect to sexual orientation. CONCLUSIONS: Although most YM/TWSM identified family in their support networks, friends were most often cited as PrEP adherence support figures. Interventions to increase PrEP adherence should consider integrated social network and family-based approaches.