As the formal powers of the European Parliament increased with successive treaty changes, its committees' administrations have seen a parallel growth. We argue that such administrative capacity is necessary but not sufficient for acting on those formal powers. Administrative capacity has to be combined with political capacity in order to muster policy impact in European Union decision-making. By differentiating between intra-institutional administrative and inter-institutional political capacity, we offer a fine-grained conceptualization of policy capacity while broadening the theoretical and empirical understanding of the European Parliament's administration as an organizational structure of (in)formal working practices, intra-institutiona...