Two projects dealing with biological invasions in the 6th Framework Programme of the European Union, DAISIE and ALARM, are described and some results presented. The main aim of DAISIE (2005-2008) was to build a pan-European inventory of alien species from various taxonomic groups (plants, invertebrates, vertebrates) in terrestrial, freshwater and marine environments. ALARM (2004-2009), an ongoing Integrated Project of the 6 FP, covers biological invasions as one of the pressures threatening biodiversity in Europe, together with climate change, environmental chemicals and loss of pollinators.