The aim of this paper is twofold. First, we offer a methodological reflection on how the explanatory virtues of economic theories can be assessed in a systematic way. Second, we use that theoretical apparatus to study the explanatory virtues of Transaction Cost Economics (TCE, henceforth). Precisely, we are primarily interested in assessing the progress within TCE with respect to its explanatory power rather than directly comparing TCE's explanatory virtues to alternative theories. The paper offers also some general insights into the way we compare economic theories.