  We present spectroscopy of individual stars in 26 Magellanic Cloud (MC) star
clusters with the aim of estimating dynamical masses and $V$-band mass-to-light
($M/L_V$) ratios over a wide range in age and metallicity. We obtained 3137
high-resolution stellar spectra with M2FS on the \textit{Magellan}/Clay
Telescope. Combined with 239 published spectroscopic results of comparable
quality, we produced a final sample of 2787 stars with good quality spectra for
kinematic analysis in the target clusters. Line-of-sight velocities measured
from these spectra and stellar positions within each cluster were used in a
customized expectation-maximization (EM) technique to estimate cluster
membership probabilities. Using appropriate cluster structural parameters and
corresponding single-mass dynamical models, this technique ultimately provides
self-consistent total mass and $M/L_V$ estimates for each cluster. Mean
metallicities for the clusters were also obtained and tied to a scale based on
calcium IR triplet metallicites. We present trends of the cluster $M/L_V$
values with cluster age, mass and metallicity, and find that our results run
about 40 per cent on average lower than the predictions of a set of simple
stellar population (SSP) models. Modified SSP models that account for internal
and external dynamical effects greatly improve agreement with our results, as
can models that adopt a strongly bottom-light IMF. To the extent that dynamical
evolution must occur, a modified IMF is not required to match data and models.
In contrast, a bottom-heavy IMF is ruled out for our cluster sample as this
would lead to higher predicted $M/L_V$ values, significantly increasing the
discrepancy with our observations.
