Hélio Oiticica (1937-80) was one of the most brilliant Brazilian artists of the 1960s and 1970s. He was a forerunner of participatory art, and his melding of geometric abstraction and bodily engagement has influenced contemporary artists from Cildo Meireles and Ricardo Basbaum to Gabriel Orozco, Dominique Gonzalez-Foerster, and Olafur Eliasson. This book examines Oiticica’s impressive works against the backdrop of Brazil’s dramatic postwar push for modernization. From Oiticica’s late 1950s experiments with painting and color to his mid-1960s wearable , Small traces a series of artistic procedures that foreground the activation of the spectator. Analyzing works, propositions, and a wealth of archival material, she shows how Oiticica’s practice recast—in a sense “folded”—Brazil’s utopian vision of progress as well as the legacy of European constructive art. Ultimately, the book argues that the effectiveness of Oiticica’s participatory works stems not from a renunciation of art, but rather from their ability to produce epistemological models that reimagine the traditional boundaries between art and life.