Objective : This study aims to understand the effects of Group Cognitive Rehabilitation Therapy (GCRT) based on Occupational Therapy Intervention Process Models (OTIPM) on the Activities of Daily Living (ADL), cognitive function, and depression of mild dementia patients, and to suggest the basic data for GCRT for dementia patients. Methods : GCRT was applied two times a week for eight weeks to 14 mild dementia patients who visited the Gwanak Center for Managing Dementia and the Seongbuk Center for Dementia in Seoul between August 2007 and July 2008. The research was conducted for a total of 12 weeks including a tracking evaluation conducted four weeks later. Based on OTIPM, the GCRT was applied by selecting a compensation model, an education teaching model, a restorative model, and an acquisitional model. Moreover, a one-group pretest-post test design, which is a quasi-experiment and research tool, was also applied in order to verify the effects of the rehabilitation therapy on the subjects' ability toward ADL, cognitive function, and depression. Results : A significant effect was confirmed (p<.05) from the GCRT, which was comprised of a verbal fluency test, MMSE-KC, ACL, and AMPS. In contrast, there was no significant effect in MMSE-KC, which was comprised of Boston naming, word list memory, constructional praxis, and word list recall tests. No significant effect on improving the depression syndromes from GDS was found either. Conclusion : It seems that GCRT based on OTIPM has an effect on the improvement of the ability toward ADL and on the cognitive function of mild dementia patients living in a community.