  We calculate the Isgur-Wise function on the lattice, simulating the light
quark with the Wilson action and the heavy quark with a direct lattice
implementation of the heavy-quark effective theory. Improved smearing functions
produced by a variational technique, MOST, are used to reduce the statistical
errors and to minimize excited-state contamination of the ground-state signal.
Calculating the required matching factors, we obtain $\xi'(1)=-0.64(13)$ for
the slope of the Isgur-Wise function in continuum-HQET in the $\barMS$ scheme
at a scale of $4.0 $GeV.
