Worker cooperatives have a long and tortured history, but recently they have been advancing globally on a more stable foundation than before. In this essay I provide a theoretical context for the current growth of cooperatives, drawing on Marxist theory to illuminate their potential. I also consider the sociology and economics of worker cooperatives, in addition to expounding and evaluating their history in the United States. A case-study of a cooperative printing press in Jamaica Plain gives a more intimate portrayal of worker co-ops, and hopefully provides lessons for future cooperators. I interpret society as on the cusp of a triumphant advance of cooperativism; the main purpose of this essay is to explain how and why this advance will occur.