Of special concern was whether prisoners' level of adjustment, as measured on Barron's Ego Strength Scale (ES), was related to the preference for either a peer therapist (an inmate trained in counseling) or a professional therapist. Subjects also completed the Marlowe-Crowne Social Desirability Scale (M-C SDS). Subjects were 98 inmates from an Indiana Federal Penitentiary who indicated their preference for therapists before and after viewing videotapes of role-played therapy vignettes. Each inmate evaluated each therapist on five problems (alcohol, drugs, recidivism, work release, and authority). A videotape rating scale was used. Analysis of results showed that the ES scale is a poor predictor of prisoners' preference for therapist types. A significant majority of subjects preferred the professional therapists, although the peer therapist was preferred on the work release problem. There was no support for the speculation that inmate peer therapists should be employed on prison treatment teams. Because peer therapists are employed in increasing numbers in prisons, it is recommended that process and outcome studies of peer therapists be undertaken with objective criteria established to assess the therapy. Tabular data and bibliography (about 90 items) are included, and appendixes reproduce testing materials.