When speaking about international police cooperation in Europe of the 20th century, the necessity of bounding police resources must be revealed in relation with economic development and with the existence of more accessible travel possibilities, for criminals as well. Growing together in an unified Europe and finding ways of accepting police cooperation beyond linguistic, institutional and operational differences, turned up to be an even bigger concern than the threats themselves. Building trust and suitable institutions for combating criminality on a European basis was as difficult as it was to recognize that alone, isolated in a national wide system of internal security, the results would not give too much credit for success. In the global village set up by modern communication forms, police forces had to learn the new language of acting together, in order to control and prevent transborder crime, illegal migration and terrorism. This article tries to show some, in the authors opinion, relevant issues of this learning process, in the general framework of the European Community.