The goal of the workshop is to bring together world experts in the field of hadronic shower development, to establish a collaborative effort that will lead to a better understanding and simulation of hadronic showers relevant to hadron calorimetry at the ILC and LHC, neutrino fluxes and atmospheric showers. The workshop will evaluate existing event generator and transport codes. Before the workshop we expect to carry out a bench marking analysis. Various hadronic shower simulation scenarios will be submitted to code developers and the results will be presented at the workshop. The workshop should identify the shortcomings of existing hadronic shower simulations and develop a collaborative plan to improve our understanding of showers and investigate the need to acquire new data to improve shower models.