The past decade has seen dramatic growth in research on treatments for the psychiatric problems of older adults. An emerging evidence base supports the efficacy of geriatric mental health interventions. The authors provide an overview of the evidence base for clinical practice. They identified three sources of evidence-evidence-based reviews, meta-analyses, and expert consensus statements-on established and emerging interventions for the most common disorders of late life, which include depression, dementia, substance abuse, schizophrenia, and anxiety. The most extensive research support was found for the effectiveness of pharmacological and psychosocial interventions for geriatric major depression and for dementia. Less is known about the effectiveness of treatments for the other disorders, although emerging evidence is promising for selected interventions. Empirical support was also found for the effectiveness of community-based, multidisciplinary, geriatric psychiatry treatment teams. The authors discuss barriers to implementing evidence-based practices in the mental health service delivery system for older adults. They describe approaches to overcoming these barriers that are based on the findings of research on practice change and dissemination. Successful approaches to implementing change in the practices of providers emphasize moving beyond traditional models of continuing medical education to include educational techniques that actively involve the learner, as well as systems change interventions such as integrated care management, implementation toolkits, automated reminders, and decision support technologies. The anticipated growth in the population of older persons with mental disorders underscores the need for a strategy to facilitate the systematic and effective implementation of evidence-based practices in geriatric mental health care.