  We determine the mass of the black hole at the center of the spiral galaxy
NGC 4258 by constructing axisymmetric dynamical models of the galaxy. These
models are constrained by high spatial resolution imaging and long-slit
spectroscopy of the nuclear region obtained with the {\em Hubble Space
Telescope}, complemented by ground-based observations extending to larger
radii. Our best mass estimate is $\MBH = (3.3 \pm 0.2) \times 10^7 \MSun $ for
a distance of 7.28 Mpc (statistical errors only). This is within 15% of $
(3.82\pm 0.01) \times 10^7 \MSun$, the mass determined from the kinematics of
water masers (rescaled to the same distance) assuming they are in Keplerian
rotation in a warped disk. The construction of accurate dynamical models of NGC
4258 is somewhat compromised by an unresolved active nucleus and color
gradients, the latter caused by variations in the stellar population and/or
obscuring dust. These problems are not present in the $\sim 30$ other black
hole mass determinations from stellar dynamics that have been published by us
and other groups; thus, the relatively close agreement between the stellar
dynamical mass and the maser mass in NGC 4258 enhances our confidence in the
black hole masses determined in other galaxies from stellar dynamics using
similar methods and data of comparable quality.
