This longitudinal study investigated the presence of a moderating effect of pregnancy planning on the relationship between marital status and parenting satisfaction of couples experiencing the transition to parenthood and verified whether this moderating effect is mediated by role overload. Data were collected from 150 Canadian couples during the 3rd trimester of pregnancy and at 9 months postpartum. Findings reveal that when the pregnancy is planned, the poorer parenting satisfaction reported by cohabiting fathers in comparison with their married counterparts can be explained by cohabiting men's higher levels of role overload. Women's levels of parenting satisfaction are also influenced by their own and their partner's experiences of role overload. Results are discussed in terms of the respective values and lifestyles of cohabiting and married couples and specifically in terms of their different attitudes toward egalitarianism.