The informal contours of the wider European administrative space: EU Agencies' de facto cooperation with non-EU member states.

An increasing number of studies highlight the importance of EU agencies as sites of differentiated administrative integration with non-EU member states. This research usually concentrates on formal agreements that regulate third countries' access to the EU agencies. Beyond a limited number of case studies, little is known about how these formal agreements play out in practice. Moreover, little is known about whether cooperation also unfolds informally in the absence of formal agreement – and under what conditions. Drawing on two databases of third country de jure and de facto cooperation with (nearly all 37) EU agencies, this paper maps the informal contours of agencies' de facto cooperation with third countries over time and examines the impact of agency and third country properties on the relationship between formal and informal cooperation. This research contributes to a fuller understanding of the role of EU agencies in the construction of a wider European administrative space and the conditions under which external differentiated integration unfolds in the EU's transgovernmental sphere.