The design and implementation of a program is usually based on a set of explicit or implicit assumptions about the actions required to solve a social problem and reasons why the problem should respond to the particular action. More specifically, there are two kinds of assumptions underlying a program: prescriptive and descriptive. The descriptive assumptions (change model) describe causal processes that lead to goal attainment. The prescriptive assumptions (action model) prescribe the program components and activities that will enable a program to function. Program theory is a systematic configuration of stakeholders' prescriptive assumptions (what actions are required to solve a social problem) and descriptive assumptions (why the problem will respond to these actions) underlying a program—whether explicit or implicit assumptions are made by stakeholders (Chen, ...