  We develop the improved ladder approximation to QCD in order to apply it to
the heavy quark mesons. The resulting Bethe-Salpeter equation is expanded in
powers of the inverse heavy quark mass 1/M, and is shown to be consistent with
the heavy quark spin symmetry. We calculate numerically the universal leading
order BS amplitude for heavy pseudoscalar and vector mesons, and use this to
evaluate the Isgur-Wise function and the decay constant F_B. The resulting
Isgur-Wise function predicts a large charge radius, rho^2 = 1.8 - 2.0, which
when fitted to the ARGUS data corresponds to the value Vcb = .044 - .050 for
the Kobayashi-Maskawa matrix element.
