Cool Stars 14 - Submitted Abstract # 41 This version created on 05 October 2006 Subsolar Metallicity Substellar Objects Adam Burgasser, Massachusetts Institute of Technology Over the past few years, astronomers have uncovered a handful of low-temperature, metal-poor objects with halo or thick disk kinematics and peculiar spectral and photometric properties. These include the first examples of L subdwarfs - metal-poor analogs of the L dwarf spectral class - and a few slightly metal-poor T dwarfs. Metal deficient brown dwarfs provide useful empirical tests for brown dwarf atmospheric and evolutionary models, and are probes of the halo mass function down to and below the (metal-dependent) hydrogen burning limit. In this contributed talk, I will review the optical and near-infrared signatures of subsolar metallicity in L and T dwarfs, discuss how these signatures relate to differences in the structure and chemistry of their atmospheres, and provide suggestions on how to classify these objects. I will conclude by describing methods of optimizing searches for metal-poor L and T dwarfs, with the ultimate goal of measuring the halo mass function into the substellar regime. ----------------------------------