PHOT will be used at 60, 90 and 160 micron, and CAM at 12 micron
 to investigate the spectral energy distributions (SEDs) of 5 or 6
 distant radio galaxies at redshifts of 2.3 to 4.3. The SEDs will
 provide insight into the nature of the far-IR emission of the
 most distant known galaxies, when the universe was only 10 percent
 of its present age.
 The SEDs will allow us to study the ubiquity of dust, and
 therefore processed material in these young objects, the
 luminosity of the dust emission and the temperatures of the
 emitting dust components. Derived color temperatures will allow
 an assessment of the relative importance of the active nucleus
 and of possible starbursts in producing the observed emission.
 The results will have consequences for such topics as
 heavy element production, the early evolution and formation
 of galaxies, and the role of strong starbursts in the early
 universe. The CAM observations will probe hot dust associated
 with an obscured quasar nucleus predicted to exist by unified
 models of quasars and radio galaxies.
 ISO provides the only way of probing the temperature-sensitive
 Wien part of the blackbody curve. Measurements to be obtained
 with the new SCUBA bolometer array at the JCMT will complement
 the SEDs at long wavelengths.

 We have the largest sample of distant radio galaxies available,
 from which we have selected the best candidate sources. The
 targets are all z > 2 galaxies with detected CO, submm continuum
 emission, or other evidence for the presence of copious neutral
 gas. The data will provide a unique view of the neutral inter-
 stellar (and probably starforming) interstellar medium in the
 most distant galaxies known to us.