The joint production of paintings by more than one artist was not uncommon in the past: a number of Old Masters had assistants do much of the work on their paintings, executing images that had been planned by the master. Yet prior to the twentieth century very few paintings were actually signed by more than one artist. Early in the twentieth century, many important conceptual artists occasionally co-authored paintings or drawings, but consistent co-authorship of paintings, sculptures, and photographs is a practice that is novel to the late twentieth century. These recent instances have generally involved pairs of conceptual artists. The English team, Gilbert and George, is the most important pair that has consistently produced co-authored works; they have executed all of their work jointly since 1969, when they made Singing Sculpture, their first and most famous piece. A number of pairs of young conceptual artists had worked closely together earlier in the century, but they did not formally co-author their work, perhaps because of the art world's commitment to the ideal of the autonomous artist. Since the critical and economic success of Gilbert and George has demonstrated that this resistance can be overcome, co-authorship has become more common among younger conceptual artists, and this trend is likely to continue in future
