Activities of intelligence agencies have recently moved into the focus of public review all over Europe. The publication of the Snowden documents revealed a surveillance practice of unknown extent. Intelligence surveillance no longer focuses on state organizations or political decision-makers alone; technical innovation rather allows unprovoked mass surveillance of individual communication. In view of this development and politicians have demanded legal limitations of such practices. This Handbook takes into account the various facets of intelligence activities in Europe spanning from chapters on intelligence operations to intelligence cooperation within different policies in Europe, within the EU and beyond (e.g. NATO).