This monograph synthesizes current information from the various fields of cognitive science in support of a new theory of mind. Most psychologists study horizontal processes like memory. Fodor postulates a vertical and modular psychological organization underlying biologically coherent behaviours. This view of mental architecture is consistent with the historical tradition of faculty psychology while integrating a computational approach to mental processes. One of the most notable aspects of Fodor’s work is that it articulates features not only of speculative cognitive architecture but also of current research in artificial intelligence. – Part I. Four accounts of mental structure; – Part II. A functional taxonomy of cognitive mechanisms; – Part III. Input systems as modules; – Part IV. Central systems; – Part V. Caveats and conclusions. M.-M. V.