In this article an attempt is made to give a better insight into the psychiatric investigation of unfitness for work, pertaining to the application of social legislation (ZW, AAW/WAO). A psychiatrist is often required to make a report in a case where a patient does not agree with the judgment of the Adjudicating Officer of the Social Security Office about his work capacity, and appeals to the Social Security Appeal Tribunal. The methodology of this investigation into unfitness is sequentially discussed. In each part (complaints, medical history, family background, psychiatric examination) extra attention is given to those questions which were important in defining working (in)capacity on mental grounds. Extra attention is also given to informing colleagues and to the processing of data that determines the disablement. A tentative table of functional limitations is also constructed in an attempt tot provide a better alternative to the hitherto accepted tables. It is the author's aim with this contribution to improve the quality of psychiatric assessment of disability.