Community interventions that use social network analysis to identify and involve influential individuals are promising for behavior change. However, youth friendships are often unstable. The current study examined the stability of the youth selected as influential in a friendship social network, that is, the degree to which youth selected at one time point were also selected at subsequent time points. Influential youth, also called popular opinion leaders (POLs), were selected to be part of a community‐wide sexual violence prevention initiative. POLs were selected based on high in‐degree (number of times an individual was nominated as a best friend by another student). We found that POLs were unstable: only 29.81%–41.01% of POLs were stable across time. The percentage of POLs who were stable decreased across time. No factors (social identities, behavioral, attitudinal) consistently predicted POL stability. Although these findings are in need of replications, social network interventions for youth may need to repeatedly select new POLs to account for instability.