In 2006, the OECD Development Assistance Committee (DAC) Ministers of Development expressed a desire to move towards more effective collective responses to governance issues, particularly as regards corruption. In 2007 the OECD Policy Paper on Anti-Corruption “Setting an Agenda for Collective Action” proposed developing a voluntary code of conduct for co-ordinated donor responses to deteriorating corruption contexts. The DAC Network on Governance (GOVNET) was tasked with producing a framework for joint responses. To inform this work the Anti-corruption Task Team (ACTT) of the GOVNET commissioned this retrospective study of how donors have responded to corruption in practice in the past, so as to understand better the opportunities, constraints and incentives for more effective collective responses and to establish principles on which a draft code of conduct could be based.