This study examined the role of friends' attitudes in adolescent smoking (N = 203). Growth mixture modeling was used to identify three trajectories of smoking behavior from ages 12 to 14 years: a "low-rate" group, an "increasing-rate" group, and a "high-rate" group. Adolescents' own and their friends' attitudes at age 11 years were not significantly related to smoking. However, in the increasing-rate group (compared with the low-rate group), friends' attitudes interacted with both adolescents' own and friends' social preference (i.e., likeability). The link between friends' attitudes and membership in the increasing-rate group was stronger for early adolescents with low social preference scores and for early adolescents with friends who had low social preference scores. Other than for the high-rate group, for which causal factors of smoking may be located early in childhood (e.g., family and personality or temperamental characteristics), the combination of low social preference and friends who hold a positive attitude toward smoking is associated with escalating cigarette use among young adolescents. (Contains 3 tables, 3 figures and 4 footnotes.)