This volume contains the main contributions to the 14th International Conference on Recent Progress in Many-Body Theories (RPMBT14) held at the Technical University of Catalonia, Spain, in July 2007. This conference, which was first held in Trieste in 1979, is devoted to new developments in the field of many-body theories, which are being applied and developed in a rapidly growing number of fields. The emphasis is twofold: progress in the technical aspects of microscopic theories and a review of recent applications of many-body techniques. In addition to the more traditional topics, such as nuclear physics and quantum liquids, the present volume also includes the most recent results on atomic physics, cold Bose and Fermi gases, phase transitions and quantum information. Moreover, the volume contains the lectures of the winners of the 2007 Feenberg Medal and 2007 Kuemmel Award, as well as their laudatios.