Proceedings of the First International Workshop on Multiple Partonic Interactions at the LHC. MPI'08. Perugia, October 27-31, 2008

The objective of this first workshop on Multiple Partonic Interactions (MPI) at the LHC, that can beregarded as a continuation and extension of the dedicated meetings held at DESY in the years 2006 and2007, is to raise the profile of MPI studies, summarizing the legacy from the older phenomenology athadronic colliders and favouring further specific contacts between the theory and experimental com-munities. The MPI are experiencing a growing popularity and are currently widely invoked to accountfor observations that would not be explained otherwise: the activity of the Underlying Event, the crosssections for multiple heavy flavour production, the survival probability of large rapidity gaps in harddiffraction, etc. At the same time, the implementation of the MPI effects in the Monte Carlo modelsis quickly proceeding through an increasing level of sophistication and complexity that in perspectiveachieves deep general implications for the LHC physics. The ultimate ambition of this workshop is topromote the MPI as unification concept between seemingly heterogeneous research lines and to profit ofthe complete experimental picture in order to constrain their implementation in the models, evaluatingthe spin offs on the LHC physics program. The workshop is structured in five sections, with the first onededicated to few selected hot highlights in the High Energy Physics and directly connected to the otherones: Multiple Parton Interactions (in both the soft and the hard regimes), Diffraction, Monte CarloGenerators and Heavy Ions.