To determine whether behavioral change as a result of environmental stimulation can be reported in individualized terms for the aged with organic brain syndrome or senile dementia, a program of multimodal group interactive therapy was started in an extended care facility. During a 1.5-year period, the study included 108 residents, whose average age was 84 years. The technique used was a combination of modified Reality Orientation, Remotivation, Activity and Milieu therapies. Thirteen groups residing in different wings of the facility were treated for 55 sessions by 11 activity specialists and 2 elderly volunteers under the supervision of the consulting clinical psychologist. Data were collected on emerging behavioral changes with respect to awareness, attention, verbalized ideation, voice quality, speech quantity, sociability, self-care, quality of affect, energy level, expressed somatic concern and physical movement. Of the initial 108 residents, 80 had chronic brain syndrome of varying severity or senile dementia. During treatment, 35 of these 80 residents (44 percent) were improved, 17 (20 percent) were unchanged, 14 (18 percent) became worse, and 14 (18 percent) remained unrated. The results warrant a redifinition of the psychotherapeutic approach. It should include factors other than the severity and chronicity of disease in determining the prognosis for behavioral change in geriatric institutional residents.