This paper proposes a new conceptual tool to study norm dynamics in world politics. Termed norm subsidiarity, it concerns the process whereby local actors create rules with a view to preserve their autonomy from dominance, neglect, violation, or abuse by more powerful central actors. After a theoretical discussion of the definition, motivations, and effects of norm subsidiarity, the paper offers a case study of normative action against Cold War alliances (especially South East Asia Treaty Organization) by a group of Third World leaders led by India’s Jawaharlal Nehru at the Bandung Asia-Africa Conference in 1955. It then offers examples from Latin America, the Middle East, and Africa to highlight the practice of norm subsidiarity. The paper contributes to the literature of international relations in three main ways. First, it reminds constructivist international relation scholars of the importance of understanding norm creation as a bottom-up process, marked by significant contestations and feedback. Second, it highlights the normative behaviors of Third World countries and their regional institutions, a neglected aspect of the literature on norm dynamics. Finally, the theory and practice of norm subsidiarity shed more light on the agency role of Third World countries in world politics.