Some of the most innovative art of the past decade has been created far outside conventional galleries and museums. In a parking garage in Oakland, California; on a pleasure boat on the Lake of Zurich in Switzerland; at a public market in Chiang Mai, Thailandartists operating at the intersection of art and cultural activism have been developing new forms of collaboration with diverse audiences and communities. Their projects have addressed such issues as political conflict in Northern Ireland, gang violence on Chicago's West Side, and the problems of sex workers in Switzerland. Provocative,...