Abstract This article reports on a quantitative study of 1,117 cases of transposition of directives in five EU Member States and eight policy sectors between 1978 and 2002. It finds significant cross-sectoral performance differences, which complicate generalization from studies of only one sector. These differences can be partly explained by systematic cross-sectoral differences in transposition deadlines given, the share of Council versus Commission directives, and the legal implementation measures used.