Over the last decade, EU research has made great strides in understanding the EU decision-making process. Conversely, the dynamics unfolding after a legislative act (directive, regulation) is passed have been largely overlooked. Some of these acts remain in force in their original form for several years while others are amended or even abolished soon after their adoption. What factors account for this variability? Answering this question may ultimately contribute to enhance our understanding of the forces influencing policy change in the EU. To this end, the present study develops an event history model accounting for the factors that make the amendment of EU legislative acts more likely by simultaneously controlling for the possibility of a law repeal. More specifically, we test whether changes in institutional rules – in intra-Council voting and in legislative procedures - influence “if and when” an act is amended. The empirical test of the model employs Franchino’s selection of major laws integrated with information on amendments to these laws drawn from EURlex between 1958 and 2002.