The understanding of internal security in the post-Cold War period considerably differs from the perception of the concept prevailing in the previous era. The qualitative change in the meaning of internal security has been caused by many factors of both intra-state as well as – paradoxically – international character. However, internal security is understood in different ways in various states because of their history and traditions, political and legal systems, current policies in internal affairs etc., and also due to their membership in international organizations. In particular, the European Union (EU) member states had to adopt an approach to internal security which has been evolving during the last two decades because of the impact of solutions implemented by the EU in the field of internal security. Another very important factor is the boom of alternative concepts of security after the end of the Cold War which are moving away from the traditional, state-security paradigm towards new subjects of security – e.g. the ecosystem (environmental security), social groups (societal security) and, finally, the individual human being (human security). It is the concept of human security that has become well-established, firstly in the policies of the United Nations (UN), and more recently within the European Union, as well. The topic of this volume is the understanding of internal security in states that are members of the European Union. A particular interest of the analysis has been the question to what extent the concept of human security has influenced the current perception of internal security. There are two main concepts of human security, which are widely known as the Japanese school (“freedom from want”), a broad approach, focused on meeting basic human needs, and the narrower approach of the so-called Canadian school, postulating “freedom from fear”, i.e. protection of rights and civil liberties as well as personal safety. In this volume the impact of both these concepts of human security on the meaning of internal security is explored.