Toward a galaxian luminosity-metallicity relation spanning ten magnitudes

We describe the two projects by which we are assembling a database of near-IR luminosities and direct oxygen abundances for both high- and low-mass star-forming galaxies in the nearby Universe. This will eventually allow us to construct the first reliable and homogeneous luminosity-metallicity relation, to be compared to theoretical models of galactic evolution, and to the relations for galaxies at higher redshifts.