  We consider the transverse-momentum (q_T) distribution of Drell--Yan lepton
pairs produced in hadron collisions. At small values of q_T, we resum the
logarithmically-enhanced perturbative QCD contributions up to
next-to-next-to-leading logarithmic accuracy. At intermediate and large values
of q_T, we consistently combine resummation with the known next-to-leading
order perturbative result. All perturbative terms up to order alpha_S^2 are
included in our computation which, after integration over q_T, reproduces the
known next-to-next-to-leading order result for the Drell--Yan total cross
section. We show and discuss the reduction in the scale dependence of the
results with respect to lower-order calculations, estimating the corresponding
perturbative uncertainty. We present a preliminary comparison with Tevatron Run
II data.
