The star-formation rate (SFR) as a function of rest-frame B-band luminosity for long-duration GRBs (circles), short-duration GRBs (squares), and field galaxies (stars).  The gray line indicates the correlation for long GRBs.  Short GRBs have lower SFRs for a fixed luminosity, indicating a longer characteristic time scale associated with the star formation in these galaxies.  The inset shows the distribution of specific star formation (star formation per unit mass), where short-duration GRBs are very similar to field galaxies.  From \cite{Berger2014}.