Occupants in air-tight houses and with poorly maintained mechanical ventilation systems have stimulated the study of health hazards of housing. Five hundred houses were inspected, to diagnose the relation between lay-out, construction, technical services, interior decorations and potential indoor air pollution or problems with noise and safety. The occupants were interviewed about ventilation behaviour and activities that produce pollutants or hazards. The relations between technical performances of houses, occupant behaviour and exposure to health risk were analysed. The result is a list of indicators that mark in particular the exposure to house dust mite, mould, legionella pneumophila bacteria, fine dust, noise, extreme discomfort and safety hazards. Tools for the evaluation of health performances were developed and tested. The strategy and the indicators presented in this thesis are the basis for the Checklist Healthy Housing, available in versions for households and professional users (see www.toetslijstgezondwonen.nl).