Objectives: Conversations shape health behaviors. However, individuals vary in susceptibility to conversational influence and in their neural responses that track such influences. We examined whether activity in brain regions associated with social rewards and making sense of others’ minds was related to drinking following conversations about alcohol. We studied ten social groups of college students (total N = 104 students; 4760 total observations) across two University campuses. Methods:We collected whole-brain fMRI data while participants viewed photographs of the faces of peers with whom they tended to drink at varying frequencies (i.e., drinking vs. non-drinking peers). Next, using mobile diaries, we tracked alcohol-related conversations and alcohol use twice daily for 28 days. Results: On average, talking about alcohol was associated with a higher probability of drinking the following day. Controlling for baseline drinking, participants who responded more strongly to drinking peers—with whom they drank more frequently— in brain regions associated with social rewards and mentalizing showed higher susceptibility to conversational influence on drinking. Conversely, stronger neural responses to non-drinking peers—with whom they drank less frequently—decoupled the link between alcohol conversations and next-day drinking. Conclusions: These findings conceptually replicate prior findings linking peer conversations and drinking behavior in a longitudinal, ecologically valid setting, and provide new evidence that brain sensitivity to peers may exacerbate or buffer conversational susceptibility to drink.