Abstract : The concept of "general works" is widely used in libraries, for many purposes : indexing, call numbers, library signs, acquisitions, etc. However, general works are seldom the subject of real acquisitions plans. Moreover, the use of the concept raises many difficulties and inconsistencies, because of its looseness. This work aims at questioning from a semantic point of view the concept of general works, so as to determine its meaning and its limits. We will also study the way in which it appears in the principal classifications employed in libraries. After this clarification, we will propose guidelines to give general works a real documentary contents, in order to build projects of collection development.