Rapid assessment for decision making is a major goal of the initial psychiatric interview in walk-in clinics, emergency psychiatric services, and the ambulatory services of community mental health centers. To accomplish this task, the clinician must learn to elicit specific data to confirm or refute clinical hypotheses rather than gather a complete history. This report, in formulating a hypothesis generating and testing approach for the initial psychiatric examination, proposes 16 hypotheses that organize the clinical data necessary for most decisions. This approach is intended to help the clinician make efficient use of limited time, guard him from coming to premature closure in the collection of data, and provide a stimulus for the exploration of relevant but neglected clinical questions.