A theory of change (ToC) is an explicit theory of how and why it is thought that a social policy or program activities lead to outcomes and impacts.[1] ToCs are used in the design of programs and program evaluation, across a range of policy areas.
Theories of change can be developed at any stage of a program, depending on the intended use. A theory of change developed at the outset is best at informing the planning of an initiative. Having worked out a change model, practitioners can make more informed decisions about strategy and tactics. As monitoring and evaluation data become available, stakeholders can periodically refine the theory of change as the evidence indicates. A theory of change can be developed retrospectively by reading program documents, talking to stakeholders, and analyzing data. This is often done during evaluations reflecting what has worked or not in order to understand the past and plan for the future.