Atomic jets and molecular out?ows from Young Stellar Objects (YSOs) are among the most spectacular of astrophysical phenomena. Approaching this topic, one gets immediately trapped by the breathtaking beauty of the op- calimagestakenfromEarthorSpacewithmoderntelescopes,onlytodiscover soonafterthatthephysicsthatregulatestheirpropertiesisevenmoreintri- ing. Out?ows are believed to play a fundamental role in the formationprocess of a new star and its planets, as they could be the principal agent for the removal of the excess angular momentum from the star-disk system. Their generation mechanism, still poorly understood, involves a complex interplay of gravity, turbulence, and magnetic forces, while their propagation into the surrounding medium a?ects through the action of shocks and ionizing fronts the way the parent cloud evolves, and hence the future generations of young stars. A deep understanding of stellar jets is therefore fundamental to any theory of Star Formation. The motivation of the four-year JETSET (Jet Simulations, Experiments and Theory) Marie Curie Research Training Network is to build an int- disciplinary European research community focused on the study of jets from youngstars. Thenetworkscienti?cgoalsfocusonunderstanding(1)thedr- ing mechanisms of jets around young stars; (2) the cooling-heating processes, instabilities, and shock structures in stellar and laboratory jets; and (3) the impact of jets on energy balance and star formation in the galactic medium. Central to these overall goals are the series of JETSET schools dedicated to the training of our young researchers in key jet topics.