This dissertation examines the post-1968 work of the Argentine artist and architect Clorindo Testa (1923-2013), arguing that 1968 represents a major turning point in his career, when he rethought his artistic practice in response to the dramatically altered institutional, political, and economic circumstances of Argentina in the late 1960s. Over the years between 1968 and 1974 Testa worked out the logic of this transformation and established the conceptual, stylistic, and thematic basis for the final four decades of his career. His studio production from this period is bracketed by the creation of two major, architecturally-themed works: the 1968 site-specific installation Prop for a Museum (Apuntalamiento para un museo) at National Museum of Fine Arts in Buenos Aires and the 1974 mural-sized Dwelling, Transportation, Work, and Recreation (Habitar, circular, trabajar y recrearse), conceived for the Galería Carmen Waugh, in the same city. This dissertation proposes that, on an international level, Prop for a Museum stands out as one of the pioneering works of the emergent conceptualist practice of institutional critique, and that together with Dwelling, Transportation, Work, and Recreation it represents a kind of manifesto for the new, post-1968 direction in the artist’s work.