Does development research need reinventing? If it does, why now and in what ways does it need to be changed? These are the questions addressed by the articles in this issue of the IDS Bulletin, many of which were presented at IDS40, the fortieth anniversary conference, in September 2006. They were also posed by the 46 Roundtables held throughout the world in 2006, organised by IDS partners and alumni, which preceded and helped frame the conference agenda.