In the Netherlands there are considerable health differences by marital status; differences are found in subjective and objective health measures, in mental and physical health, and in morbidity and mortality. In general divorced people have the most and married people the least health problems. Married people have less health problems than unmarried people living with a partner. Differences in mortality by marital status are smaller among women than among men. There are two explanatory theories: the social causation theory (marital status influences health) and the selection theory (health influences marital status). Both theories play a role in the explanation of the health differences. The effect of marital status on health among men is mainly mediated by psychosocial factors, whereas material circumstances are the principal intermediary factor among women. Health intervention among unmarried men should be aimed at intensifying social support from the environment, among divorced women it should be aimed at improving material conditions.