  We consider the transverse-momentum (q_T) distribution of Higgs bosons
produced at hadron colliders. We use a formalism that uniformly treats both the
small-q_T and large-q_T regions in QCD perturbation theory. At small q_T (q_T
<< M_H, M_H being the mass of the Higgs boson), we implement an all-order
resummation of logarithmically-enhanced contributions up to
next-to-next-to-leading logarithmic accuracy. At large q_T (q_T \gtap M_H), we
use fixed-order perturbation theory up to next-to-leading order. The resummed
and fixed-order approaches are consistently matched by avoiding double-counting
in the intermediate-q_T region. In this region, the introduction of unjustified
higher-order terms is avoided by imposing unitarity constraints, so that the
integral of the q_T spectrum exactly reproduces the perturbative result for the
total cross section up to next-to-next-to-leading order. Numerical results at
the LHC are presented. These show that the main features of the q_T
distribution are quite stable with respect to perturbative QCD uncertainties.
