  I discuss recent theoretical work on the formation and evolution of galaxies
paying particular attention to the ability of current models to make detailed
comparisons with observations of the galaxy population both nearby and at high
redshift. These models suggest that much (perhaps most) star formation in the
universe took place in objects that are already detected in deep galaxy
samples. In addition, they predict that systems with large star formation rates
are unlikely to be much more abundant in the past than they are at present.
Recent data show that the star formation rate in the nearby universe is, in
fact, a substantial fraction of that required to make all the stars seen in
galaxies, and that the observed abundance of objects forming stars at rates in
excess of 10 solar masses per yr is approximately the same at redshifts of 1.25
and 3.25 as it is at z = 0. Both the epoch of galaxy formation and ``typical''
protogalaxies may already have been observed but not recognised. Thermal
emission from dust in such protogalaxies could be detected by a large
millimeter array, and molecular line observations could explore the dynamical
state of the gas in the more massive systems.
