Allan Kaprow

18 Happenings in 6 Parts, Reuben Gallery, New York, 1959 Kaprow had coined "happening" in a 1958 essay, and this is the piece that put the word into circulation. He split a loft into three rooms with semi-transparent plastic walls and ran six parts with three events each, all at once, so nobody could see everything. Visitors were handed three cards telling them where to sit and when to change rooms at the sound of a bell, which made the audience part of the score rather than spectators. The work lives on through Kaprow's score, photographs and later re-doings, including one at Haus der Kunst in Munich in November 2006, which he authorized shortly before his death.