Proponents of group counseling with public offenders have recommended the use of unstructured counseling groups as a means of helping offenders change attitudes that have contributed to their problems with the law. Many public offenders, especially those who use illicit drugs, often see people as objects to be used for their own purposes. The 26 study participants were all members of a residential drug treatment center. The marathon group session was facilitated by three counselors and a psychologist. Offenders had similar personal and social backgrounds; they had spent an average of 5.3 years in prison for various offenses, including burglary, drug sales, and arson. The process of the group followed a defined sequence. Following initial reluctance to discuss personal feelings, several residents confronted staff members on certain issues. After this point, residents began interacting to reveal personal problems, primarily related to their families. A semantic differential was used to assess the attitude changes of participants. A nonrandom pretest/posttest control group design was used to assess the outcome of the marathon experience, and general linear models procedure was used to analyze the pretest and posttest data. Results indicate that marathon group counseling can be effective in producing certain attitude changes among public offenders with histories of illicit drug use. Although significant results were not obtained on a large number of scales, there were significant differences between pretest and posttest scores of the control and marathon group participants on the reality, counselors, and guilt scales. Two tables and 26 references are included.