Many countries have created agencies specialized in the fight against corruption both as an alternative to recourse to the judicial system and because the complexity of the corruption phenomenon is escalating. The fight against corruption requires specific skills in a variety of fields, including law, finance, economics, accounting, civil engineering, and social sciences. The main functions of such agencies are law enforcement, prevention, policy development, and coordination. A comparative review of different agencies around the world reveals that their effectiveness in curbing corruption differs highly across countries. The most successful examples are those of Singapore and Hong Kong. Such a review also shows that when the agencies do not deliver “success”, failure is not entirely attributable to them. A major source of failures is the relationship with governments and donors in terms of funding, independence, accountability, and transparency.