The article aims to elucidate the variation in governance quality (administrative and judicial quality) among those post-communist countries which were granted EU membership in the late 1990s. It is argued that the differences in governance development between the more advanced first-wave EU candidates (Luxembourg group) and the less advanced second-wave EU candidates (Helsinki group) cannot be solely explained by historical domestic factors (pre-communist and communist legacies), but by more recent and external factors, such as EU conditionality. The impact of the EU on governance quality is revealed in an indicator-based comparative analysis, which yields two main findings. First, EU conditionality had a stronger impact on governance quality in the Helsinki group than in the Luxembourg group. Second, despite a substantial impact on the formal and efficiency-related aspects of gover-nance, persisting structural and power-related aspects exposed the limits of EU conditionality.