  We present the results of an effort to identify and study a sample of the
likely progenitors of elliptical (E) and lenticular (S0) K+A galaxies. To
achieve this, we have searched a sample ~11,000 nearby (m(r)<16) early-type
galaxies selected by morphology from the Sloan Digital Sky Survey (SDSS) Main
spectroscopic sample for actively star-forming E and S0 galaxies. Using
emission line ratios and visual inspection of SDSS g-band images, we have
identified 335 galaxies from the SDSS Fourth Data Release (DR4) as actively
star-forming E and S0 galaxies. These galaxies make up about 3% of the total
early-type sample and less than 1% of all Main galaxies with m(r)<16. We also
identified a sample of ~400 K+A galaxies from DR4 with m(r)<16; more than half
of these are E and S0 galaxies. We find that star-forming early-type galaxies
and K+A galaxies have similar mass distributions; they are on average less
massive than typical early-type galaxies but more massive than the average
star-forming galaxy. Both of these types of galaxies are found in higher
fractions among all galaxies in lower density environments. The fractions of
star-forming E and S0 galaxies and E and S0 K+A galaxies depend on environment
in nearly the same way. Model spectra fit to the stellar continua of the
star-forming E and S0 galaxies showed that their properties are consistent with
star formation episodes of <1 Gyr in duration. The modelling results imply that
on average, the star formation episodes will increase the stellar masses by
about 4%. There is also evidence that the star-forming regions within these
galaxies are rotationally supported.
