  Radio continuum surveys can detect galaxies over a very wide range in
redshift, making them powerful tools for studying the distant universe. Until
recently, though, identifying the optical counterparts of faint radio sources
and measuring their redshifts was a slow and laborious process which could only
be carried out for relatively small samples of galaxies.
  Combining data from all-sky radio continuum surveys with optical spectra from
the new large-area redshift surveys now makes it possible to measure redshifts
for tens of thousands of radio-emitting galaxies, as well as determining
unambiguously whether the radio emission in each galaxy arises mainly from an
active nucleus (AGN) or from processes related to star formation. Here we
present some results from a recent study of radio-source populations in the 2dF
Galaxy Redshift Survey, including a new derivation of the local star-formation
density, and discuss the prospects for future studies of galaxy evolution using
both radio and optical data.
