Cohesion Policy accounts for the largest area of expenditure in the EU budget. Because of its scope and redistributive nature, evaluation is particularly important. Policy analysis tends to overlook the evaluation stage. Few empirical studies seek to apply theory to EU policy evaluation. This article questions the relevance and usefulness of theorizing evaluation practice, exploring positivist, realist, and constructivist perspectives upon approaches to evaluating Structural Funds Programmes. It illustrates how political science theories can provide scholars with useful insights into the way EU policy evaluation is carried out. It develops a toolkit for analyzing real-world approaches to evaluation and then applies it to three separate Cohesion Policy programmes. The analysis shows how, from a theoretical perspective – and contrary to the mixed methods rhetoric of the European Commission – positivism remains the dominant approach when evaluating the Structural Funds and considers why this is so, identifying the ability to demonstrate efficiency and effectiveness, cost, influence, and evaluation culture as key characteristics.