Using a longitudinal sample of Swedish midadolescents, variations from the normal transition into regular drinking habits were proposed to be linked to particular types of peer relationships. The interpersonal ecology for variations from the age-normative patterns was assumed to be the association with younger, older, or full-time working peers. As predicted, analyses for midadolescent males and females (N = 1,012) at age 14 years showed that having younger peers as friends was related to a lower prevalence of and less frequent drunkenness in midadolescence as compared to having only same-age peers as friends. Similar results were evident for association with older or with working peers. The differential impact of peers, which was evident at the age of 14 years, was still significant 17 months later but not at the age of 26 years. Discussion emphasized the need to assess differential influences on timing in the transitions in social behavior in adolescence.