This paper reviews the literature addressing four process issues associated with the effectiveness of treatment for offenders: 1) therapist characteristics; 2) clients' perceptions of the therapist; 3) the therapeutic alliance; and 4) the group climate of treatment. The general clinical literature is briefly summarized and then these issues are examined in adult offenders and in juvenile offenders. Although there is a limited set of research articles on process issues in offender treatment it is possible to make some reasonably sound conclusions. Each of the four process features appraised facilitates the attainment of treatment goals and account for a greater proportion of the variance in the sought-after changes with treatment of offenders than do the procedures used to achieve these changes. This proportion of variance accounted for is significantly greater than is true in the treatment of nonoffending clients. Suggestions are offered for future research. References (Published Abstract)