Since 2007, the European Centre for Disease Prevention and Control (ECDC) has supported I-MOVE (influenza monitoring vaccine effectiveness), a network to monitor seasonal and pandemic influenza vaccine effectiveness (IVE) in the European Union (EU) and European Economic Area (EEA). To set up I-MOVE, we conducted a literature review and a survey on methods used in the EU/EEA to measure IVE and held expert consultations to guide the development of generic protocols to estimate IVE in the EU/EEA. On the basis of these protocols, from the 2008/09 season, I-MOVE teams have conducted multicentre case–control, cohort and screening method studies, undertaken within existing sentinel influenza surveillance systems. The estimates obtained include effectiveness against medically attended laboratory-confirmed influenza and are adjusted for the main confounding factors described in the literature. I-MOVE studies are methodologically sound and feasible: the availability of various study designs, settings and outcomes provides complementary evidence, facilitating the interpretation of the results. The IVE estimates have been useful in helping to guide influenza vaccine policy at national and European level. I-MOVE is a unique platform for exchanging views on methods to estimate IVE. The scientific knowledge and experience in practical, managerial and logistic issues can be adapted to monitor surveillance of the effectiveness of other vaccines.