Although the notion of a nosological category suggests that disorders within the same category have roughly similar etiology and natural history, reality in psychiatry is rather different. Not only between diagnostic categories but also within most diagnostic categories enormous variation in long-term outcome has been observed. This issue is of utmost importance for general practitioners and nurse practitioners given their position in the health care system as primary care provider and referral agent to specialty mental health care. My presentation will address the question what role long-term outcome should play in the classification of mental disorders, especially in the context of primary care and the stepped care model of collaborative care. To this end I will use longitudinal data of mostly depression collected in European general population and primary care studies.