The past decade has witnessed the proliferation of mechanisms of operational co-operation in Europe’s area of criminal justice. A key feature of these developments has been the growing focus on the collection, processing and transfer of personal data at the heart of operational co-operation. The aim of this chapter is to map and provide a critical assessment of this move to what can be called ‘data-driven’ operational co-operation in EU criminal law. The chapter will provide a taxonomy of data-driven operational co-operation by focusing on three levels: on the level of the establishment of EU structures and mechanisms of data collection, analysis and exchange (the establishment of EU databases and their interoperability); on the level of the establishment of data-driven operational co-operation mandated by EU law at the national level (the establishment of financial intelligence units will be used as a case-study, as well as the development of transnational networks of co-operation between these agencies); and on the level of the development of the privatisation of data-driven operational co-operation via co-opting the private sector (telecommunication providers, airlines, internet providers) in the fight against crime. Throughout the chapter, the challenges of these developments to fundamental rights (in particular the rights to privacy and data protection) and the rule of law will be highlighted.