The growing cultural pluralism of US society requires clinicians to examine the impact of cultural factors on psychiatric illness, including on symptom presentation and help-seeking behavior. In order to render an accurate diagnosis across cultural boundaries and formulate treatment plans acceptable to the patient, clinicians need a systematic method for eliciting and evaluating cultural information in the clinical encounter. This article describes one such method, the Cultural Formulation model, expanding on the guidelines published in DSM-IV. It consists of five components, assessing cultural identity, cultural explanations of the illness, cultural factors related to the psychosocial environment and levels of functioning, cultural elements of the clinician-patient relationship, and the overall impact of culture on diagnosis and care. We present a brief historical overview of the model and use a case scenario to illustrate each of its components and the substantial effect on illness course and treatment outcome of implementing the model in clinical practice.