Background. A considerable body of research has established that transitions out of marriage are generally deleterious for mental health and some have examined transitions out of cohabitation. In this study we depart from these established areas to investigate the effects of poor mental health on the duration and outcome of cohabitations and on the time to, and likelihood of, repartnering after both cohabitation and marriage.

Method. Samples came from the British Household Panel Survey, 1991–2001. These were: (1) 447 cohabiting spells; (2) 5571 paired person-years during cohabitation; (3) 508 spells after cohabitation; (4) 1197 person-year observations within those spells; (5) 869 spells after marriage; and (6) 2736 person-year observations within those spells. Life tables, log-rank tests, multinomial logit and proportional hazard models were used. Mental health was measured by the 12-item General Health Questionnaire.

Results. Poor mental health increased the risk of dissolving a cohabiting union for both men and women. Poor mental health reduced the risk of repartnering after a cohabiting union but had no effect on the risk of repartnering after a marriage. Other factors such as past marital status, age and parental status also had significant effects.

Conclusions. This study provides evidence that poor mental health during a cohabiting union increases the chances of that union dissolving instead of turning into marriage and poorer mental health immediately after a transition out of a cohabiting union is associated with reduced chances of repartnering.