The present study, using data from the English and Welsh Civil and Social Justice Survey, compares the characteristics of spouses and cohabitants, and aims to examine how relationship type influences the experience of civil law problems generally and problems associated with relationship breakdown in particular. Socio-economic differences between married and cohabiting respondents were found to be largely a function of age. Little difference in stability of relationships was evident from these data once age, in particular, was accounted for. The presence of children tended to increase the stability of relationships regardless of form. Cohabitants, particularly those with children, were more likely to report family-related problems, though there was evidence that many of these problems concerned earlier relationships. Problems associated with relationship breakdown routinely resulted in adverse consequences such as ill-health, loss of income, loss of a home or domestic violence. Adverse consequences were especially common for those without resident children, particularly stress-related ill-health; but lone parents experienced more adverse consequences than parents with care who had repartnered. These findings prompt discussion about various issues, including the relationship between marriage and family success.