Brown dwarfs in the Hyades and beyond?

We have used both the Low-Resolution Imaging Spectrograph and the High Reso lution Echelle Spectrograph on the Keck telescopes to obtain spectra of 12 candidate members of the Hyades identified by Leggett & Hawkins. All of the objects are chromospherically active, late-type M dwarfs, with Ho: equival ent widths varying from 1 to 30 Angstrom. Based on our measured radial velo cities, the level of stellar activity, and other spectroscopic features, on ly one of the 12 stars has properties consistent with cluster membership. W e consider how this result affects estimates of the luminosity and mass fun ction of the Hyades. Five of the 11 field stars have weak K I lambda lambda 7665, 7699 and CaH absorption as compared with M dwarf standards of the sa me spectral type, suggesting a lower surface gravity. Two of these sources, LH 0416 + 14 and LH 0419 + 15, exhibit significant lithium 6708 Angstrom a bsorption. Based partly on parallax measurements by the US Naval Observator y (Harris et al.), we identify all five as likely to be young, pre-main-seq uence objects in or near the Taurus-Auriga association at distances of betw een 150 and 250 pc. A. comparison with theoretical models of pre-main-seque nce stars indicates masses of less than 0.05 M..