In this radical book, architects, historians, and theorists survey the inventive, low cost work being done in obscure places to make architecture into a force for sustainable growth and social justice. The efforts are Utopian not charitable in aim. This new breed of architect-activists is endeavoring to diversity if not reinvent their profession by engaging in an "exchange" of ideas, techniques, and visions of right living with people almost always relegated to silence and invisibility. The book opens with theoretical essays, each specially commissioned, from a stellar cast. Michael Sorkin assesses "the site of the social" in architecture; David Gersten draws on John Hejduk's legacy to consider architecture's role as "a gatekeeper" between the world "out there" and everyday life; historian Jonathan Massey proposes "five ways to change the world"; with Chris Marker's films as a springboard, Mabel O. Wilson recounts her search for traces of Valentino Deng's ravaged village in South Sudan. Subsequent essays form a field guide to "exchange" projects from Harlem to Port-au-Prince to Serekunda and Indore, a few still unbuilt, all virtually unknown to students of architecture. Jae Cha, Peter Clegg, Simón Vélez, and famed modernist Balkrishna Doshi demonstrate the benefits of easily found and/or scavenged materials, including bamboo. Money is saved; no gas-guzzling, earth-leveling machines are needed; residents rely on their own building skills and their (not the architect's) notions of home and community. In other, also generously illustrated essays, Milton S.F. Curry, Hansy Better Barraza, Jennifer Lee, and Pablo Castro present varied alternatives to ghettoizing large groups in bleak housing complexes and urban "deserts." The book ends with an epilogue in which Alberto Pérez-Gómez shows that expression of the "poetic imagination" is as important as pragmatic concerns in the pursuit of social justice in architecture.