SummaryTo provide a parsimonious description of prisoners with alcohol and drug use histories, a clustering algorithm was applied to a set of treatment‐relevant psychosocial variables obtained from a survey of 269 male incarcerated Canadian offenders. A stable five group solution was uncovered. The groups are differentiated mainly in terms of the seriousness of their alcohol and drug problems but each group has its own particular constellation of other features: one group was relatively problem‐free; one abused drugs other than alcohol and seemed to be leading a generally criminal lifestyle; the third group abused only alcohol and was more socially stable; and the final two groups abused both alcohol and other drugs differing in that one reported needing more emotional assistance and the other showing signs of organic deficits.