This thesis explores the supervision of Europol’s processing and exchanges of personal data, and questions whether the supervisory arrangements are adequate to ensure the protection of personal data of individuals. Europol’s competences have recently been expanded in 2022 further emphasising its role as the EU criminal information hub. This entails for instance a strong network of partners, and high levels of collection, processing, and exchanges of data. “Agencies must be subject to an effective system of supervision and control.” – The Commission in 2001, in its White Paper, already noted this need for strong supervision over EU Agencies. However, since then, most academic work focused on their accountability or judicial review. This thesis draws from the previous literature in the field, to develop a theoretical framework of the concept of supervision. It argues that supervision is a process aimed at achieving other values, such as accountability. It is thus distinct from the notion of accountability, but also from judicial review and control. This theoretical framework is then used in an empirical evaluation of Europol’s processing of personal data, and of Europol’s exchanges of personal data in two situations: (1) in the hotspots in Greece; and (2) through the Schengen Information System. In my thesis, I argue that there is insufficient supervision over Europol’s processing operations, and a complete supervisory lacuna of the exchanges. I thus conclude with three policy recommendations. First, there is a need to increase the level of transparency in the supervisory relationship itself. This means stronger transparency from Europol, but also proactiveness by the supervisory authorities in this regard and more generally through investigations for example. Second, the supervision itself must be impactful and strengthened, for example by increasing ex ante supervision, and the follow-ups. Finally, it is key to introduce the supervision over the exchanges of personal data, to not leave them fully unsupervised. This thesis provides an in-depth analysis of Europol’s intelligence role and its supervision. It is a first cut that paves the way for further research in the area. Agencies, particularly within the Area of Freedom, Security and Justice, are increasingly relying on data and data-sharing as integral to and a means of governing. Frontex, for example, has seen its intelligence role grow exponentially within the past years. This expansion of competence by EU agencies must go hand in glove with strong supervision and I provide several pathways for this.