All impaired driving offenders were voluntary participants and anonymity was insured. Fifty-two individuals, with a mean age of 36 years and placed on probation during 1985 and 1986 for driving while intoxicated (DWI), agreed to participate. An additional 61 inmates, with a mean age of 35 years, in a large Ontario institution for at least four DWI convictions participated. Four subtypes of impaired driving offenders were identified: (1) individuals who possess comparatively little pathology aside from the fact that they are alcoholics; (2) working men who drink too much, but are not necessarily alcohol-dependent; (3) unassertive, maladjusted offenders who are not all alcohol-dependent, but who may drink excessively; and (4) individuals with aggressive, hostile, and sensation-seeking behaviors and attitudes who seem to lack an internal locus of control. Correctional treatment alternatives are discussed in relation to these findings. 24 references.