Abstract: Observations over the past decade of star-forming galaxies have revealed several surprises, including a similarly in galaxy evolution across a wide variety of conditions and the rapid production of luminous, and presumably massive, galaxies. I will describe these puzzles in more detail, then show a model we have been developing for star formation regulated by a combination of a temperature-dependent initial mass function and heating due to starlight, cosmic rays and, at very high redshift, the cosmic microwave background. This model produces an attractor, near-equilibrium solution which is consistent with observations of the star-forming "main sequence" over a broad redshift range. Additional solutions to the same equations may correspond to other observed phases of galaxy evolution including quiescent galaxies.