Over the past decades, the size and role of the private security industry in the European Union (EU) has grown considerably, demonstrating that security provision increasingly goes well beyond the state. So far however, most criminological research has focused – often in isolation from other disciplines – on describing contemporary private security industry developments in the individual EU Member States, or the role of private military companies as part of EU’s foreign Common Security and Defence Policy. However, what is not yet understood is the extent to which non-military private security provision, policy and regulation at EU level have developed over time and how the private security industry has contributed to the EU’s internal security strategies. By studying long-term shifts in the role of the security industry within such EU security policy, this innovative project aims to provide, for the first time, comprehensive theoretical knowledge on transnational processes of privatisation in the European security landscape. To achieve these objectives, this interdisciplinary research combines well-elaborated historical criminological methods and policy theory. Historical and contemporary data are analysed using the Multiple Streams Approach in order to gain an understanding of how and under which conditions private security became a topic on the EU policy agenda. The findings will make an important contribution to the field of criminology, history and political sciences.