  I present the results of a multiyear survey of very low mass stars and brown
dwarfs, at high spectral resolution. The spectra were gathered with the HIRES
echelle at the Keck Observatory. Some of these objects are stellar and others
are substellar (or ambiguous). Early indications that such objects can be
rapidly rotating but display little H-alpha emission turn out to be commonly
true. This is the opposite of the relation between rotation and activity in
solar-type stars. The H-alpha surface flux drops precipitously at the bottom of
the main sequence, and seems to be related to the luminosity or temperature of
the objects. There is a general trend to higher rotation velocities as one
looks at objects of lower luminosity. I discuss several possible explanations
for these results. The dynamos for these objects are probably fully turbulent,
driven by convection, and thus more directly related to the object's
luminosity. They may be quenched when the rotational velocities become too fast
in comparison to the convective velocities
  (supersaturation). Another possibility is that the atmospheres of the cooler
objects are becoming sufficiently neutral to decouple atmospheric motions from
the field. Either of these could explain why young brown dwarfs can be
magnetically active while older brown dwarfs are not. A final possibility is
that instead of being quenched, the field configuration in rapid rotators
changes to a less conducive form for dissipative heating. This could explain
why flares are occasionally seen on generally inactive objects.
