The case of apartheid in South Africa was unique because it institutionalized an socio-juridical arrangement diametrically opposite to the norms which has framed the gestation of the international order after World War II. The remarkable contradiction catalyzed a chain reaction in fighting the South-African regime, and the anti-apartheid activism could operate one of the most dynamic transnational advocacy networks, developing channels of dialogue and a wide range of strategies to combat on domestic, regional and international spheres. This study - anchored in the constructivist literature on transnational activism - will discuss the formalization and operation of the antiapartheid transnational advocacy network and its operational tools, like the boomerang pattern, by analyzing its influence on the implementation of economic, strategic and social sanctions against the South African segregationist regime.