  The parton model as developed for semileptonic B decays is applied to the
inclusive decay B to J/Psi+X. We calculate the momentum spectrum of the J/Psi
using a one-parameter distribution function for the heavy quark, taken from
production experiments, and compare our results with recent data from CLEO
which fixes the distribution parameter epsilon_p. An analogous calculation is
carried out in the ACCMM model where the data determines the Fermi motion
parameter p_f. The models give a good description of the data, provided in each
of them the parameter in the distribution function is chosen to correspond to a
softer b quark momentum distribution than that commonly used in studies of
semileptonic B decays. In particular we arrive at epsilon_p = O(0.008) and p_f
= O(0.55 GeV), respectively. The latter value (p_f = 0.5 GeV) produces in the
ACCMM model 10^2*|V_ub/V_cb|^2=1.03, which removes a former supposed
discrepancy with the ISGW model. Finally, the strength of the effective color
singlet coefficient is found to be a_2 = O(0.28) in both models.
