  We present results from a high-resolution spectroscopic survey of 45 L
dwarfs, which includes both very low-mass stars and brown dwarfs. Our spectra
allow us to derive a significant number of new rotational velocities, and
discover a slowly rotating (in projected velocity) L dwarf that allows more
accurate measurement of spectroscopic rotations for these objects. We measure
chromospheric activity (and often its variability) through the H$\alpha$
emission line. Our primary new result is good evidence that magnetic braking
dominates the angular momentum evolution of even brown dwarfs, although
spindown times appear to increase as mass decreases. We confirm that activity
decreases as effective temperature decreases, though a larger fraction of L
dwarfs are active than has previously been reported. Essentially all active
objects are also variable. We confirm the lack of a rotation-activity
connection for L dwarfs. We find a minimum limit for rotational velocities that
increases with later spectral types, rising from near zero in older mid-M stars
to more than 20 km s$^{-1}$ for mid-L objects. There is strong evidence that
all L dwarfs are rapid rotators. We derive a braking law that can depend on
either temperature or mass which can explain all the rotational results and
provides an age dependence for the angular momentum evolution. It is clear that
angular momentum loss mechanisms in smaller and cooler objects become more
inefficient starting at the fully convective boundary.
