Despite the benefits for children and families of fathers who are involved positively with their children, most parenting programs in the United States and globally focus on and collect evaluation data from mothers almost exclusively. Engaging fathers is still viewed as a complex endeavor that is only somewhat successful. In this article, we summarize what is known about engaging fathers in parenting programs, then argue that programs are most effective when coparenting is the focus early in family formation. We rely on two decades of the Supporting Father Involvement program as an example of an initiative that has been effective at recruiting and retaining fathers and mothers in various cultural and national contexts. When programs are inclusive in content and focus on process, are sensitive to differences within and across families, and recognize parents as experts on their children, they are more successful in recruiting and retaining diverse groups of fathers and families.