EC directives must be transposed into the national legal order of the member states within a specified deadline. Although member states are obliged to notify their transposition measures, they often fail to comply with these deadlines. Distinguishing between domestic and EU-related factors, this study examines transposition failure and delay of EC directives from 1986 to 2002. Notification failure is found to be more likely when there is conflict between the member states during the EU legislative process. National patterns of transposition timeliness are shown to vary significantly, and higher levels of complexity and increased use of parliamentary legislation, as well as more federalist and pluralist structures, contribute to delayed compliance.