During the 1990s, states experimented with various mandatory welfare-to-work strategies, culminating in the passage of the federal Personal Responsibility and Work Opportunity Reconciliation Act in 1996. This law replaced the Family Support Act of 1988, which marked the first time in national policy that welfare recipients with children as young as 3 years old (or younger, at state option) were required to participate in work preparation activities through the Job Opportunities and Basic Skills Training (or JOBS) Program. As such, policy makers sought information on the impact of these mandatory programs not only on the economic well-being of families but also on the development and well-being of their children particularly, preschool-age children. Consequently, in designing the JOBS Evaluation (later renamed the National Evaluation of Welfare-to-Work Strategies, or NEWWS), federal officials requested a “Child Outcomes Study” to examine short- and longer-term impacts of the JOBS Program on children of enrollees, with a focus on children who were 3 to 5 years old at study entry. The Child Outcomes Study (COS) was designed to assess the impacts of an experimental manipulation of a policy requirement (or mandate) and is a direct test of how changes in this policy context affect children as they move into middle childhood. After providing some background on the JOBS program, this chapter presents a theoretical rationale for why and how a program aimed at the economic well-being of adults may influence children, summarizes findings from the COS, and proposes a revised theoretical framework for investigating effects of welfare policies on children and families.