This PhD thesis addresses the issue of cross-border cartels (CBCs). The effects of CBCs on developing countries are particularly pronounced, with such countries importing billions in goods from industries engaged in price-fixing conspiracies. The thesis explores the problems encountered by young or small competition authorities in investigating CBCs and interacting with mature or larger competition authorities, the sometimes-inconsistent enforcement landscape, and the conflicting incentives at stake. In evaluating these problems, the research proposes to disaggregate the types of CBCs into five distinctive categories: multinational, transnational, regional, export and import CBCs. It thereafter explains why international, regional and bilateral informal cooperation is the most powerful way for competition authorities to tackle CBCs and how the perspective of the vast majority of jurisdictions have shaped the international dynamics in the area of cartel enforcement. Based on an inter-disciplinary approach, the thesis proposes experimental solutions which young and small competition authorities can adopt to improve international, regional and bilateral cooperation in the area of cartel enforcement. Primarily in regard to transnational and regional CBCs, the thesis provides a triple building-block process to improve cooperation between mature or large and young or small competition authorities; and a two-tier stage to foster regional cooperation between young but large authorities and young and small competition authorities in Latin America.