The Local Group’s dwarf galaxies are near enough for exquisitely detailed, resolved stellar spectroscopy and diverse enough to conduct experiments on dark matter and chemical evolution.  I have collected medium-resolution spectra for thousands of stars in many dwarf galaxies in the Local Group.  Innovative techniques applied to these spectra recover velocities precise to a few km/s and detailed abundances precise to 0.1 dex.   Although Milky Way satellites and field dwarf galaxies are different in many ways, their velocity dispersions show that both types of galaxy pose a serious challenge to cold dark matter.  Both types also obey the same mass-metallicity relation despite the large diversity of star formation histories and detailed abundance ratios.