The foundation boasts a collection of some 22,000 Basque-themed posters dating from 1970 to the present. Agirre began collecting posters in the mid 70s, and his efforts have proven to be nothing short of pioneering, as many of these posters cannot be found elsewhere, especially the politically-themed posters from the 70s and 80s. Other posters available at the foundation cover areas as diverse as trade unionism, green movements, feminism, antimilitarism and Basque culture.

These posters are also being classified and catalogued at present, and will gradually be made available to the public as these works progress.