I discuss observations of two traditional age indicators, chromospheric
activity and kinematics, in late-M and L dwarfs near the hydrogen-burning
limit. The frequency and strength of chromospheric activity disappears rapidly
as a function of temperature over spectral types M8-L4. There is evidence that
young late-M and L dwarfs have weaker activity than older ones, the opposite of
the traditional stellar age-activity relation. The kinematics of L dwarfs
confirm that lithium L dwarfs are younger than non-lithium dwarfs.Comment: to appear in proceedings of Ultracool Dwarf Stars: Surveys,
Properties and Spectral Classification (Lecture Notes in Physics), eds. Jones
and Steele. 12 page