How can research have the greatest impact on those with the greatest need? First, we need to document the needs. Epidemiological studies, including studies in Latino populations, have tracked not only the prevalence of psychiatric disorders but also the use of services in various facets of our society. More recently, NIMH funded a large, regionally diverse, six-site collaborative study to examine the effects of ethnicity on clinical diagnosis and treatment assignment among African-American, Latino, and Caucasian patients with mood disorders. In addition to epidemiological studies, a critical part of the NIMH strategy includes large-scale, practical treatment trials in real-world health care settings to study treatment of such disorders as schizophrenia, depression, and bipolar disorder. Studies such as the Clinical Antipsychotic Trials of Intervention Effectiveness (CATIE) for schizophrenia and Alzheimer's disease, the Sequenced Treatment Alternatives to Relieve Depression (STAR*D) for treatment-resistant depression, and the Systematic Treatment Enhancement Program for Bipolar Disorder (STEP-BD) represent the first and largest studies of their kind.