Attempting to put in place an evaluation of collections implies a certain number of logistical constraints and problems of resource management and human relations. In regional libraries as elsewhere, a refined definition of the service missions must precede all considerations of documentation policy. In the regional library of Yvelines, only the adult book sector has, for the moment, adopted an enlarged plan from that existent. In the current stage, evolution relies essentially on the state of the morale of the employees, and not really on their working habits. The examination of different statistical results obtained has given rise to reflection on the utility of a regular appreciation and uniformity of practices, as well as on the numerous supplementary questions it induces.