Using the instrumental variable approach on nationally representative, individual-level data on middle-aged pension participants in China, this study quantifies the peer effect in the context of forming pension expectations. The study confirms the existence of the peer effect in forming pension expectations in the community. The probability of having optimistic pension expectations significantly increases by 0.309 percentage points if the proportion of optimists in the community increases by 1 percentage point. Moreover, the study explores the channels through which the peer effect operates and finds that the social learning channel dominates the social norms channel. The study also provides empirical evidence that village and township leaders as well as those with old pension program experience are opinion leaders in their peer group. Lastly, we find peer effects in other pension decisions, e.g., contribution size, and the contribution size increases by the proportion of optimists in the community. The study provides policy implications on ways to improve willingness to contribute to pension programs.