Spectroscopy of cool stars in the local group

The advent of 8m class telescopes, equipped with high resolution spectrographs has opened up the possibility to study the cool giant stars in the Local Group galaxies with the same detail and accuracy, which previously was only possible for Galactic stars. These spectra allow to measure accurate radial velocities and chemical abundances for a large number of elements. The radial velocities provide crucial information on the mass and internal dynamics of these galaxies. The chemical abundances allow us to break the age-metallicity degeneracy, which hampers the interpretation of the colour-magnitude diagrams, and to constrain the chemical evolution of the galaxies. In this talk I shall review the results of recent spectroscopic investigations of dwarf galaxies, satellites of the Milky Way. A very interesting picture is emerging that shows that several of these galaxies have suffered a complex star formation history and follow chemical evolutionary paths that are clearly distinct from that followed by the Milky Way. At least in one case, Sagittarius, there is clear evidence that the interaction with the Milky Way has played an important role in the evolution of the galaxy.