  We derive metal abundance estimates for a large sample of starbursting
emission-line galaxies (ELGs). Our sample is drawn from the KPNO International
Spectroscopic Survey (KISS) which has discovered over 2000 ELG candidates to
date. Follow-up optical spectra have been obtained for ~900 of these objects. A
three step process is used to obtain metal abundances for these galaxies. We
first calculate accurate nebular abundances for 12 galaxies whose spectra cover
the full optical region from [OII]3726,29 to beyond [SII]6717,31 and include
detection of [OIII]4363. Using secondary metallicity indicators R_23 and p_3,
we calculate metallicities for an additional 59 galaxies with spectra that
cover a similar wavelength range but lack [OIII]4363. The results are used to
calibrate relations between metallicity and two readily observed emission-line
ratios, which allow us to estimate coarse metallicities for 519 galaxies in
total. The uncertainty in these latter abundance estimates is 0.16 dex. From
the large, homogeneously observed sample of star-forming galaxies we identify
low metallicity candidates for future study and investigate the
metallicity-luminosity relation. We find a linear metallicity-luminosity
relation of the following form: 12 + log(O/H) = 4.059 - 0.240 M_B, with an RMS
scatter of 0.252. This result implies that the slope of the metallicity-
luminosity relation is steeper than when dwarf galaxies are considered alone,
and may be evidence that the relationship is not linear over the full
luminosity range of the sample.
