  We present a simple functional form for the joint distribution of R-band
luminosity and [OII] 3727 emission-line equivalent widths of galaxies, and show
that this form is a good fit to the galaxies in the Las Campanas Redshift
Survey. We find a relationship between [OII] equivalent width W and R-band
luminosity L_R of the approximate form: <W> \approx (10 \AA)
(L_R/L_{R,*})^{-1/2}, where L_{R,*} is the characteristic luminosity in the
Schechter function. Because this joint distribution yields information about
the relationship between stellar mass in a galaxy and its recent star-formation
rate, it can be useful for testing theories of galaxy formation. Furthermore,
understanding this joint distribution locally will make it easier to interpret
the evolution of [OII] emission-line widths to higher redshifts.
