The theory of correlated electronic systems is a fundamental area of research in condensed matter physics. It is of central importance to the study of puzzling problems such as the unusual properties of high-Tc superconductors. On the experimental side, many results are now very well consolidated. On the theoretical side, the situation is still very far from being satisfactory. In these systems the interactions among the electrons are very strong and perturbative calculations do not work. The complexity of the problem requires an international coordination for the achievement of reliable results.