Worldwide, dementia is one of the most disabling health conditions, with estimates of 24.3 million people diagnosed with dementia in 2005 and 4.6 million new cases of dementia occurring annually. This evidence-based review of the literature on depression disorders among older adults with dementia focuses on prevalence, clinical recognition, assessment, and treatment. A search of the empirical literature was undertaken to determine the extent of the problem, and the effectiveness of various pharmacological and nonpharmacological treatments.