  Self-regulation of star formation in disks is controlled by two dimensionless
parameters: the Toomre parameter for gravitational instability and the porosity
of the interstellar medium to supernova remnant-heated gas. An interplay
between these leads to expressions for the gas fraction and star formation
efficiency in disks, and to a possible explanation of the Tully-Fisher
relation. I further develop feedback arguments that arise from the impact of
massive star formation and death on protogalaxies in order to account for the
characteristic luminosity of a galaxy and for early winds from forming
spheroids.
