60 people with moderate dementia living in a french nursing homme participated in this study. Residents gave oral consent twice to participate. They were classified in groups of six residents taking into account socio-demographic and medical characteristics. Two experimental conditions were proposed : 1. a social stimulation session (36 residents) and 2. a control group without direct social stimulation (24 residents). Collected socio-demographic and medical characteristics are age, gender, timf of institutionalization, sociocultural level, marital status and diagnostic hypothesis. Before the study, scales and questionnaires were used to assess cognitive status with the Mini Mental State Examination (Folstein et al, 1975); functional abilities with Instrumental Activities of Daily Living (Lawton and Brody, 1969); depression with the Cornell Scale for Depression in Dementia (Alexopoulos et al, 1988); psychological and behavioural disorders with the Neuropsychiatric Inventory (Cummings et al, 1994); and the quality of life with the Alzheimer's Disease Related Quality of Life (Rabins et al, 1999).