Brown dwarfs, degenerate sub-stellar mass objects were predicted in the 1960s but the first bona-fide object was not discovered until 1995. About the size of Jupiter but with masses ranging from about 13-75 Mjup, these objects have effective temperatures below 2500 K and radiate mostly in the infrared. Although searches began even before the first infrared cameras became available in 1986, it was not until the advent of large format infrared arrays made it possible to carry out a Two Micron All Sky Survey that hundreds of brown dwarfs were identified in the late nineties. In 1999 when the first high-resolution, low-noise infrared spectrometer became available on the Keck 10-m telescope we (McLean, Kirkpatrick, Burgasser, & Prato) began a spectroscopic survey of a large sample of these objects to determine their spectral properties. I will describe the results to date of that project, which has already published two parts of the survey. Our current emphasis is on identifying very young brown dwarfs because these are more luminous for a given mass and significantly larger in radius. Hence they have a lower surface gravity which has an impact on line broadening. The coolest object found has Teff ~750 K, but colder objects should be possible and may be discovered by the WISE mission (PI Ned Wright, UCLA).