This paper concerns the diagnostic classification of nonaffective acute remitting psychosis (NARP), which we also term acute brief psychosis. We argue that NARP can be delineated from both schizophrenia and the affective psychoses and considered as a single diagnosis. As indicated by the term NARP, four criteria would be central to the diagnosis: 1. nonaffective, 2. acute onset (over less than two weeks), 3. recovery within a brief duration (less than six months), and 4. psychosis broadly defined. We review the rationale and the empirical evidence for this proposed classification.