Most contemporary investigations of identity have used Marcia's (1666) paradigm to describe identity formation in terms of crisis (period of questioning and searching) preceding commitment ('achievement'); commitment in the absence of crisis ('foreclosure'); crisis, no commitment ('moratorium'); and no crisis, no commitment ('diffusion'). Discriminant analyses of substance use across the achievement, moratorium, foreclosure, and diffusion identity statuses yielded significant functions for each grade comparison (7th-12th). Frequencies of experience for diffused respondents were consistently higher than estimates for the achieved and moratorium respondents; foreclosed adolescents reported the lowest frequency of experience. Diffused adolescents were about twice as likely to have tried cigarettes and alcohol, three times as likely to have tried marijuana, four times as likely to have tried inhalants, and five times as likely to have used cocaine than their foreclosed peers. The achieved, moratorium, and unclassified respondents reported frequencies of experience that fell between the two extreme groups. Implications for identifying adolescents 'at risk' and tailoring prevention/intervention efforts to developmental differences are addressed. 2 tables, 41 references. (Author abstract modified)