Developmental changes in peer factors and the influence on marijuana initiation among secondary school students.

A longitudinal sample of 3454 secondary school students in Wake County, North Carolina, was used to examine developmental changes in peer factors and their influence on marijuana initiation. Research hypotheses and questions focused on the issues of the relative influence of different types of peer factors, the causal order of peer attitudes and behaviors and respondents' behavior, and the influence of developmental changes on these relationships. Results showed that respondents perceived greater levels of use among students generally and adolescents in their neighborhoods than among their friends, but when friends' use was perceived, it was strongly related to respondents' own use. The causal order of these variables, however, was not necessarily friends influencing respondents but was probably reciprocal. Friends' drug-related behaviors, rather than attitudes, were more strongly related to respondents' likelihood of initiation. This relationship was strongest for the youngest respondents, those in the sixth grade. The strength of the relationship diminished as adolescents grew older.