Zaj was a prominent avant-garde collectives in the Spanish art scene. Going beyond the conventional divisions inherent in art disciplines, Zaj’s works arose from the union of musical, theatrical, visual, and poetic elements. The background of its early participants was predominantly in music. Juan Hidalgo and Ramón Barce from Spain, and Walter Marchetti from Italy, who founded the group in Madrid in 1964, were all acclaimed composers. In later years, the group welcomed additional notable contributors: the composer and essayist Tomás Marco, José Luis Castillejo, a poet and diplomat by profession, and the interdisciplinary artist Esther Ferrer, primarily close to performance art. In a period of activity extending from the 1970s until 1996, Zaj’s works shifted from a musical inclination to a greater emphasis on gesture, Happening, and performance, leading to a frequent link to Fluxus. Outside of Spain, the group’s activities had greater resonance, presented in Paris, London, Frankfurt am Main, Cologne, and Düsseldorf, as well as in the United States and Canada at the invitation of John Cage. Zaj's publications, invitations, and posters are distinguished by a sensitive investigation of language presented through resources close to avant-garde typography. Examples include the collection of writings by Castillejo La caída del avión en el terreno baldío (1967), and Los 4 Libros Zaj (1967). The survey A Zaj Sampler, was disseminated as part of the Great Bear Pamphlet series published by Something Else Press between 1965 and 1967. In 1996, a major retrospective of Zaj's activities was presented at the Museo Nacional Centro de Arte Reina Sofía in Madrid. Of particular relevance is the exhibition Zaj – Colección Archivo Conz, produced in collaboration with the Círculo de Bellas Artes in Madrid in 2009 and entirely dedicated to the editions published by Conz and the works preserved in his archive.