A museum is made by its collections, but, as well as conserving them and being responsible for them, it also has to spread knowledge of them, as well as having to make known everything related with research, both from the point of view of art history and museology (conservation, restoration, documentation and diffusion).

As a result of the application of the Museums Law, up to now three Catalan museums have become the Museums Section of the MNAC. Thus, between the Museu Nacional d'Art de Catalunya, the Biblioteca Museu Víctor Balaguer in Vilanova i la Geltrú, the Museu Cau Ferrat in Sitges, and the Museu Comarcal de la Garrotxa in Olot, a link has been established that completes the exhibiting discourses of these centres, with the aim of offering a better understanding of Catalan art.

Moreover, in the context of its characteristic functions with regard to the conservation of the patrimony, taken in its broadest sense, the MNAC performs a series of technical services beyond the strict field of the museum.

With regard to this, the Museum oversees the restoration of monuments and directs operations in painting, sculpture and other artistic techniques, and gives advice to other museum centres on questions referring to safety, museography and preventive conservation.

The MNAC's patrimonial collection, understood in its broadest sense, is made up of both the collections and the material in the Biblioteca d'Historia de l'Art and the Arxiu General (General Archive).