This article describes the theoretical empirical relations between mental illness, insight and behaviour.

After an outline of these concepts and their intertwining theoretical backgrounds, the results (weighted to represent the general population) are given of an investigation among 485 PSE-respondents, concerning distress, social dysfunction, insight, helpseeking behaviour and psychiatric disorder: 98% of the definite cases (PSE-ID levels, 6, 7 and 8) were (very) much troubled by their most important symptom, 78% showed moderate to severe social dysfunction, and 55% had limited insight into their problems; 50% of the respondents had consulted a professional for psychiatric symptoms at one time or another, while 20% was still under care.

These results are discussed with special regard to the so-called `belief' models for illness behaviour and helpseeking behaviour.