This study evaluated the impact of structured and unstructured marathon therapy on institutionalized female narcotic addicts. Subjects were randomly assigned to one of five groups: two structured therapy groups, two unstructured therapy groups, and a no-treatment control group. The Personal Orientation Inventory, the Adjective Check List, and a measure of self-ideal congruence were selected as the dependent variables. Results showed that marathon participants, when compared with the control subjects, became more interested in their obligations (i.e., "Self-control") and made greater efforts to be more successful (i.e., "Achievement). Because narcotic addicts have difficulty in impulse control and lack of persistence in working on their problems, it seems reasonable to assume that the addicts who participated in the marathon groups experienced therapeutic change. The results of the comparison between the structured and unstructured treatment conditions did not produce any significant results. Highly positive verbal feedback was received from the marathon participants directly after the postmeasures were administered. (Author/PC)