The complexities of markets and market environments are felt in the design and the evaluation of market systems development (MSD) programmes. The authors reflect on a recent evaluation of an MSD programme in Nepal in which they used contribution analysis as a means of navigating these complexities. The planned niceties of the proposal soon departed ways from the reality on the ground, forcing the authors to adopt a more iterative evaluation approach, while ensuring evaluative robustness. This article outlines the iterative process and what the authors have learned regarding the applicability of contribution analysis within a theory-based evaluation, in a dynamic, changing environment.