Growing numbers of men are fathering children within cohabiting unions. However, we know little about their desires for and preferred roles in making fertility decisions. To address this gap, I use data from 61 in-depth interviews with working- and middle-class cohabiting men to examine their stated preferences should their partners experience an unplanned pregnancy. For some men, the decision appears to be a relatively stable personal or political one, but most draw on their current relationships and/or financial or maturational situations when noting their desires. A subsample of 22 men from this group who have experienced pregnancies is used to explore men’s actual roles in negotiating whether a conception was terminated or carried to term. Despite the fact that most men would like to have input into decisions to abort or carry a pregnancy to term, the majority were not actually involved in making decisions with their partners (especially the decision to abort) when pregnancies occurred. Results are interpreted in light of social class differences in family formation processes.