A transfer of criminal proceedings may take place between a judicial authority from one Member State and a judicial authority in another Member State when it is in the interest of a proper administration of justice that a criminal offence is further investigated and prosecuted in the second Member State. There was a general feeling among experts on judicial cooperation in the Member States that the current practice of transferring criminal proceedings could and should be improved. Researchers from the Erasmus University Rotterdam, together with the Amsterdam Public Prosecution Office, Bielefeld University and the Belgian Federal Prosecution Office took the initiative to start a a research project on the Transfer of criminal proceedings in the EU (TROP). The project was funded by the European Commission. This report contains the conclusions of the TROP research project. It outlines the current practice of transferring criminal proceedings in the EU, it identifies the main challenges experienced by practitioners and describes possible solutions to those challenges. These solutions were tested in multiple discussions between practitioners, academics and policy makers. During the TROP research project, it became clear that the European Commission would propose a new legislative instrument on the transfer of criminal proceedings in the near future. In the report, we tried to anticipate the content of such a proposal and the discussion in the Council and in the European Parliament. To this end, we have formulated our proposals for improving the transfer of proceedings as building blocks for a possible EU-legal instrument.