While spouse similarity for psychiatric morbidity has been the object of numerous studies, most of these focused on clinical samples and, consequently, the interpretation of their results is limited by the existence of a selection bias. In this study, conducted on a sample of 845 general population couples, significant spouse similarity was observed for psychological distress and well-being, characterized by a marked symmetry in the relation between spouses' scores. The sex differences observed in many earlier studies would appear essentially to be artefactual. Spouse similarity was also found to be significant in the subpopulation of couples married less than two years, which pointed to assortative mating for psychological distress and well-being. While many studies have found educational dissimilarity and age difference between spouses to be associated with certain health variables, such as high blood pressure and coronary heart disease, these variables do not have a significant influence on individual levels of psychological distress and well-being. Spouse similarity for socio-demographic characteristics does not play a significant role in explaining spouse similarity for mental health. Consequently, assortative mating for psychological distress and well-being would appear to be primarily due to personal preference.