  The state-of-the-art of chemical evolution models for Irregular and Blue
Compact galaxies is reviewed. The resulting scenarios for the initial mass
function, the regime of star formation and the efficiency of gas outflows are
described: The IMF appears to be roughly the same everywhere; the SF has
possibly followed a bursting regime in BCGs and a more continuous regime in
Irregulars, but with significant exceptions; galactic winds must occur in some
of these galaxies, with efficiencies inversely proportional to the galaxy
potential well.
