Using the General Social Survey on Social Engagement conducted by Statistics Canada in 2003, this paper examines social capital derived from informal networks and its variation among men categorized as: (1) men with no children, and (2) men living with children in (a) intact, (b) step, and (c) lone parent families. The focus on men stems from a concern that their role in families has not been as extensively studied as that of women. The results show that married men living with children have higher social capital--measured in terms of the number of friends, relatives, and neighbors, and in their level of trust in them--than lone fathers or step fathers in cohabiting unions. Compared to child-free men, married fathers have higher social capital but also tend to have friends who are more similar to themselves in age, education, or income.