In addition to its primary mission to constrain the nature of dark energy with BAO, the Dark Energy Spectroscopic Instrument is obtaining spectra of over 12 million stars in the Milky Way and several Local Group galaxies. These spectra yield excellent radial velocity precision (~1-10km/s for most stars), as well as abundances for ~10 elements. In conjunction with proper motions from ESO's Gaia satellite, the six-dimensional phase space information being collected by DESI will enable us to set constraints on the Milky Way halo's global dark matter density profile and shape. We are also constraining the central and outer dark matter density profiles of dwarf galaxies in the Local Group. In addition we are exhaustively surveying several stellar tidal streams in the Milky Way with the goal of constraining the mass function and central density profiles of dark matter subhalos. I will describe some recent results and future plans of DESI's Milky Way working group. I will also briefly describe some on-going theoretical projects that will enable us to measure figure rotation (tumbling) of the Milky Way's dark matter halo - one of the few dynamical properties consistently predicted for Lambda CDM.