The legislative empowerment of the European Parliament (EP) has augmented the importance of committee rapporteurs as the institution’s key representatives in inter-institutional negotiations. As a result, the question of who becomes rapporteur has received quite some attention in studies of EU legislative politics and existing studies largely argue that report allocation can be explained by characteristics of the individual legislators (e.g. their experience, education, and ideological extremeness). Yet, the implicit assumption in the literature is that all of these explanations work independently from the actual policy substance of the legislative proposal to which the draft report pertains. In this study, we challenge this assumption and investigate the extent to which the explanatory power of legislator characteristics is conditioned by the complexity of the underlying legislative proposal. We hypothesize that more experienced, educated and moderate Members of the European Parliament (MEPs) are not only more likely to become rapporteurs (as shown by the existing literature), but that they draft their reports on substantively different and more complex policy proposals than their less experienced, less educated and more extreme peers. The empirical analysis of this claim is based on an original dataset combining information on the complexity of 4,000 legislative proposals issued by the European Commission between 1994 and 2020 with information on the corresponding EP rapporteurs. Our study thereby contributes an important missing puzzle piece to the growing literature on legislative organization in the European Parliament by highlighting the role of proposal complexity for the report allocation process.