This monographic dissertation traces the development of happenings and mass media art in Argentina through the works that Argentine artist Marta Minujín created between 1961 and 1968. It argues that, in its unparalleled pursuit of a mass audience, Minujín’s art articulated a populist logic that allowed it to subvert authoritarianism in an oblique manner based in dissensus. This distinguished Minujín’s practice from that of other politically radicalized Argentine artists, who had turned their art into a form of activism and overt critique of the dictatorship of General Onganía. This dissertation also demonstrates that Minujín’s media-centric happenings and environments adopted a carnivalesque strategy of “positive negation” or ambiguous mimetic excess to reveal and critique the effects of an incipient spectacle culture.