From supergiant stars to galaxies: The path to extragalactic distances

The spectroscopic study of blue supergiants in nearby galaxies can yield crucial information about the spatial distribution of extinction by dust, and can be successfully used to measure the metal content, abundance patterns, and distances of galaxies out to ~8 Mpc with current telescopes and instrumentation. We briefly review the results of an ongoing project in which the quantitative analysis of B- and A-type supergiants is used to independently test widely used metallicity diagnostics for star-forming galaxies and derive reddening-free extragalactic distances.