This article of the Global Organization of Parliamentarians against Corruption (GOPAC) gives a conceptual overview of how parliaments and parliamentarians can help to fight corruption. The paper illustrates that parliamentarians do have a potentially wide range of tools available if the political and administrative environment permits and encourages them to play such roles and if they have the knowledge and skills to take advantage of the opportunities available. A central focus of GOPAC is the development of practical tools and training for parliamentarians.