Depression is a pervasive problem in nursing home residents with Alzheimer's disease (AD). Depressive symptoms and dysphoric mood have been linked to loss of function out of proportion to the stage of AD (excess disability). Exercise is a realistic intervention which shows promise in the treatment of depression and dysphoria in this population. The long term objective for this research is to decrease excess disability due to depressive symptoms and dysphoric mood in nursing home residents with AD. The immediate objectives of this study are to: 1) Examine the effects of exercise over 16 weeks on mood and depressive symptoms in institutionalized elders with Alzheimer's disease and 2) Examine the effects of exercise over 16 weeks on excess disability in institutionalized elders with Alzheimer's disease. This study will be a randomized pretest-postest design with raters blinded to treatment. Subjects will be pre-screened for depressive symptoms and randomly assigned to one of two groups: exercise (supervised walking) or control group (social visits). Fifty subjects in the exercise group will receive up to 30 minutes of walking five times a week for four months. Another fifty subjects in the control group will receive attention in the form of social visits five times a week for the same amount of time. Depressive symptoms will be measured using the Cornell Scale for Depression in Dementia and mood will be measured with the Dementia Mood Assessment Scale and the Dementia Mood Picture Test. Excess disability will be measured using the Refined ADL Scale, The Physical Self-Maintenance Scale, and the Six-Minute Walk. Data will be analyzed using univariate and multivariate repeated measures analysis of variance. The primary test of the hypotheses will be for the interaction effect between group membership and time. Four groups of measures will be examined for their influence on the outcome measures and their potential utility as covariates in testing the hypotheses: sociodemographic measures, use of medications, comorbidity, and severity of dementia. Nursing home residents with AD are increasing in number. Most will become extremely inactive and consume a disproportionately large share of nurses' time. Depression hastens the decline in self-care abilities in nursing home residents with AD, increases distress and burden for caregivers, and may lead to complications such as falls and pressure ulcers. If found effective, this intervention may help to maintain residents with AD at the highest functional level for as long as possible.