  We present a flare rate analysis of 50,130 M dwarf light curves in SDSS
Stripe 82. We identified 271 flares using a customized variability index to
search ~2.5 million photometric observations for flux increases in the u- and
g-bands. Every image of a flaring observation was examined by eye and with a
PSF-matching and image subtraction tool to guard against false positives.
Flaring is found to be strongly correlated with the appearance of H-alpha in
emission in the quiet spectrum. Of the 99 flare stars that have spectra, we
classify 8 as relatively inactive. The flaring fraction is found to increase
strongly in stars with redder colors during quiescence, which can be attributed
to the increasing flare visibility and increasing active fraction for redder
stars. The flaring fraction is strongly correlated with |Z| distance such that
most stars that flare are within 300 pc of the Galactic plane. We derive flare
u-band luminosities and find that the most luminous flares occur on the
earlier-type M dwarfs. Our best estimate of the lower limit on the flaring rate
(averaged over Stripe 82) for flares with \Delta u \ge 0.7 magnitudes on stars
with u < 22 is 1.3 flares hour^-1 square degree^-1 but can vary significantly
with the line-of-sight.
