As the number of children with IBD is increasing, the interaction between pediatric and adult gastroenterology is gaining importance to facilitate the transition from childhood into adulthood. Moreover, it is important to take into account not only the potential differences in phenotypes and clinical evolution of IBD during the life cycle, but also the changes in environmental factors and the possible differences in patient response resulting from the latter. The articles contained in this publication are based on the presentations made during the Falk Symposium on 'IBD in different age groups' in Madrid in 2009. On this occasion, specialists in adult and pediatric gastroenterology have gathered for the first time to exchange information with regard to differences in pathogenesis, clinical manifestations, evolution and therapeutic approaches to IBD. Presenting an integrated view of the disorder, the papers of this publication will be a great help for every doctor treating IBD patients in any age group.