Using as an example a project where the Norwegian Labor and Welfare Directorate developed a comprehensive model for the follow-up of low-income families, this article demonstrates the process of developing a program theory for policy-initiated interventions. The data consist of interviews with program developers, political documents from early stages, and observations of the program's development. The results demonstrate that, although research inspired the program developers, the program was also the outcome of policy priorities, experiences from earlier projects, and input from the practice field. Multiple sources contributed to its relevance for the practice field, however, increasing its complexity. The program includes several intervention levels and follow-up areas and partially builds on elements found to be important across interventions. Although a program theory can be difficult to conceptualize within policy-initiated interventions, it is important to articulate it prior to evaluation and, if necessary, reassess it when data have been analyzed.