This article analyses the roel of the commission, the Parliamente, and the Council in the two main legislative procedures in the European Union:co-operation and co-decision(I). We use the legislative history of some 5,000 parliamentary amendements. These procedures have been the subject of agreat deal of theoretical debate. According to coventional wisdom the co-decision procedure increases the pwers of the European Parliament. Revisionist approaches, however, suggest that the conditional agenda-setting powers accorded to the Parliament by the co-operation procedure are more important than the veto powers ascribed by co-decision. Our analysis demonstrates not only that both claims are correct, but also why. On the aggregate there is a higher success rate or parliamentary amendements under co-decision (I) thatn under co-operation, just as the data published by the EP indicate. However, controlling for one of the conditions of conditional agenda setting (agreement by the commision under co-operation), conditional agenda setting empowers the EP more than veto powers. Finally, control of Commission behaviour in both procedures indicates no difference in acceptance rates between co-operation and co-decision. Our analysis explains why all three points above are true. The answer hinges on the activity of the Commission, which was more hostile to parliamentary amendments during the 1989-94 period (more amendments were rejected during this period than during any other period under both co-operation and co-decision). In addition, the power of the Commission has declined under co-decision (because it can be and is more frequently overruled by the other two players, whether its opinion is positive or negative)