This chapter identifies how developing world competition agencies can best prioritize cartel enforcement. Each jurisdiction will face a slightly different set of issues depending on its specific level of development and its socio-economic, legal and institutional endowments. Nevertheless, there are four key challenges facing most economies in transition: (1) an inability to challenge international cartels, which are potentially very damaging to developing economies; (2) obstacles to effective domestic enforcement, including the successful introduction of leniency, the imposition of penalties and the creation of competition and compliance cultures; (3) the danger of firms in concentrated markets colluding tacitly, so as to put their activities out of reach of anti-cartel enforcement and (4) collusion in public procurement, which may be particularly widespread.