  We extract the B, D, and D* meson wave functions from the CLEO data of the
decays B -> K*\gamma and B -> D^(*)\pi in the perturbative QCD framework. In
this formalism, various logarithmic corrections are organized to give the
Wilson evolution from the W boson mass down to the characteristic scale of a
decay process, which is of order of the b quark mass, and the Sudakov evolution
from the characteristic scale to a lower factorization scale of order
Lambda_{QCD}. With large logarithms organized, the b quark decay amplitudes are
evaluated reliably in perturbation theory. Below the factorization scale, QCD
dynamics is regarded as being nonperturbative, and absorbed into meson wave
functions. Because of their universality, the heavy-meson wave functions
determined in this work, can be employed to make predictions of other decay
modes. We also observe that the dependence of heavy meson wave functions on
intrinsic parton transverse momenta plays an important role in the explanation
of data.
