This study examined the relative influence of the best friends and social crowds of older adolescents on cigarette smoking. The data were examined to determine if there were differences in influence as a function of sex, conformity, or the mutuality of the friendship. This study used a longitudinal design that enabled the separation of the effects of peer influence from those of selective association. The results showed that social crowds differed in mean level of cigarette smoking, with burnouts smoking the most and jock/preps smoking the least. The majority of best friendships were homogeneous for social crowd. Best friend influence predicted change in cigarette smoking over a one-year period, while social crowd influence appeared to be minimal. Conformity was positively related to susceptibility to peer influence, although mutuality of the friendship and sex of the subject were not.