We present a high-precision infrared radial velocity (RV) study of late-type stars using spectra obtained with NIRSPEC at the W. M. Keck Observatory. RV precisions of 50 m s-1 are achieved for old field mid-M dwarfs using telluric features for wavelength calibration. Using this technique, 20 young stars in the β Pic (age ~ 12 Myr) and TW Hya (age ~ 8 Myr) Associations were monitored over several years to search for low-mass companions; we also included the chromospherically active field star GJ 873 (EV Lac) in this survey. Based on comparisons with previous optical observations of these young active stars, RV measurements at infrared wavelengths mitigate the RV noise caused by star spots by a factor of ~3. Nevertheless, star spot noise is still the dominant source of measurement error for young stars
