The project Epidemiology of Incapacity for Work was initiated and executed by the Dutch Communal Medical Service ( GMD , Gemeenschappelijke Medische Dienst ) to provide systematic insight in the characteristics of the incapacitated population of recipients of disablement insurance benefits and changes of these characteristics in time, to provide insight in problems of the implementation of the Disablement Insurance Act for the GMD and to enlarge knowledge of current problems concerning social insurances and related fields. Topics: physical condition / illness / physical disorders / health complaints / difficulties with everyday activities / trouble with motoric or sensory functions / evaluation of one's health / comparison with last year's situation / future expectations / medical treatments: number of medical doctors, number of visits, still under treatment, use of medicines, drugs prescribed, development of medical consumption, use of tranquillizers, consensus and cooperation between doctors / resumption of work, necessary provisions for resuming work / history of illness / effects on productivity / absenteeism / illness caused by job / hospitalization, received disablement benefits in the past / kind of job / job history / age when started working / voluntary breaks in working life / number of employers last 10 years / unemployment history / changes of work for health reasons/ characteristics of last job: physical and mental stress, dangers, working conditions, executive function, working hours, organizational climate, atmosphere at work, satisfaction with employer and job / attitudes regarding work / most important aspects of work / data on company respondent worked for: size, financial situation, reorganizations, company doctor / contacts with company doctor / provisions for disabled within company: different work, shorter working hours / possibilities for reemployment / contacts with controlling medical officer from GAK ( Gemeenschappelijk Administratiekantoor, Industrial Insurance Administration Office ) or industrial insurance boards / contacts with GMD personnel ( doctor or ergonomist ), satisfaction with contacts / adaption to unemployment situation, time budget, changes in daily activities, recreational activities, memberships and social activities, social contacts / attitudes with regard to receiving benefits / work ethic / reintegration into labour market / voluntary work / prospects of future work / conditions to be fulfilled / eagerness to get to work again / preferred working conditions / recent steps taken to get to work again / extra education or training / help needed / family situation / financial situation / able to manage financially / need to economize / which expenses / financial expectations / VOEG, short version of standard questionnaire for perceived health / The second wave updated the data of the first and registered changes. If respondent had gone back to work detailed data of current working situation and the process of reintegration were collected. Background variables: basic characteristics/ residence/ household characteristics/ occupation/employment/ income/capital assets/ education/ politics/ religion/ readership, mass media, and 'cultural' exposure/ organizational membership