  We compute the angular momentum, the spin parameter and the related
distribution function for Dark Matter halos hosting a spiral galaxy. We base on
scaling laws, inferred from observations, that link the properties of the
galaxy to those of the host halo; we further assume that the Dark Matter has
the same total specific angular momentum of the baryons. Our main results are:
(i) we find that the gas component of the disk significantly contributes to the
total angular momentum of the system; (ii) by adopting for the Dark Matter the
observationally supported Burkert profile, we compute the total angular
momentum of the disk and its correlation with the rotation velocity; (iii) we
find that the distribution function of the spin parameter $\lambda$ peaks at a
value of about 0.03, consistent with a no-major-merger scenario for the late
evolution of spiral galaxies.
