Parton
distributions give us precious information on how quarks and gluons
combine to give the macroscopic properties of hadrons, as for instance
the spin, as measured in laboratory. These are intrinsically
nonperturbative objects and are, since the birth of QCD, purely
empirical quantities, determined from a fitting procedure. Recently,
however, a new method has been proposed that, if successful, will be
the first ab initio calculation of these objects. In this talk, I will
overview the new method and I will present the latest results of a
lattice calculation of both polarized and unpolarized distributions.