ABSTRACT
Especially in development cooperation, theory of change still constitutes an important element in the modus operandi of evaluators. But apart from evident advantages, such as providing focus and a clear narrative, there has also been fierce criticism of its tendency to simplify things. In this essay, theories of change are discussed against the rise of ‘sustainability’ as an important value in policy and evaluation. The essay revisits the strengths and limitations of theory-based evaluation against the need to do justice to complexity, and it makes the case for a new ‘system-based’ theory of change approach. Herein, a theory of change not only serves to express the rather straightforward relationship between ‘measure’ and ‘effect’ but also specifies the necessary system requirements for sustainable impact.
