Left: Gas phase metallicity as a function of B-band luminosity.  Long-duration GRBs show a clear preference for low metallicity environments.  Short-duration GRBs, on the other hand, track field galaxies reasonably well.  Right: Comparison of short-duration GRB hosts to the fundamental metallicity relation of star-forming galaxies (gray lines), which uses a combination of star-formation rate and stellar mass.  From \cite{Berger2014}.