  We present a catalog of near-infrared (NIR) spectra and associated
measurements for 886 nearby M dwarfs. The spectra were obtained with the
NASA-Infrared Telescope Facility SpeX Spectrograph during a two-year observing
campaign; they have high signal-to-noise ratios (SNR $>100-150$), span 0.8-2.4
$\mu$m and have $R\sim2000$. Our catalog of measured values contains useful
T$_{\mathrm{eff}}$ and composition-sensitive features, empirical stellar
parameter measurements, and kinematic, photometric, and astrometric properties
compiled from the literature. We focus on measures of M dwarf abundances
([Fe/H] and [M/H]), capitalizing on the precision of recently published
empirical NIR spectroscopic calibrations. We explore systematic differences
between different abundance calibrations, and to other similar M dwarf
catalogs. We confirm that the M dwarf abundances we measure show the expected
inverse dependence with kinematic, activity, and color-based age indicators.
Finally, we provide updated [Fe/H] and [M/H] for 16 M dwarf planet hosts. This
catalog represents the largest published compilation of NIR spectra and
associated parameters for M dwarfs. It provides a rich and uniform resource for
the nearby M dwarfs, and will be especially valuable for measuring Habitable
Zone locations and comparative abundances of the M dwarf planet hosts that will
be uncovered by upcoming exoplanet surveys.
