When key stakeholders design or implement an intervention program, they usually have some ideas about how the program should be constructed and why the program is supposed to work. Program theory is defined as a set of explicit and/or implicit assumptions held by stakeholders about what actions are required to solve a social problem and why the problem will respond to these actions (Chen, 2005). A program theory is the stakeholders’ theory. However, stakeholders usually do not clearly and systematically document their program theories. In conducting theory-driven evaluations, evaluators need to facilitate stakeholders’ clarification of their program theories. Chen (2005) provides a conceptual framework for program theory that is useful in guiding evaluators in facilitating stakeholders’ clarification of their program theories. This conceptual framework is illustrated in Figure 1.