Peer influence plays a key role in the increase of risk‐taking behavior during adolescence. However, its underlying processes are not fully understood. This study examined the effects of social norms, conveyed through peer advice, on risk‐taking behavior in 15‐ to 17‐year‐old adolescents (N = 76). Participants played a card‐guessing task alone and with online peer advice. Results showed that risk‐taking increased in the presence of peers. The results further showed that adolescents took into account the uncertainty associated with gambles, as well as the social norms conveyed by peers. Our findings suggest that peers are most influential in uncertain situations and demonstrate the value of a social norms approach in examining the processes underlying peer effects.