We propose to use the LWS grating spectrometer to measure the
 continuum spectra of a sample of cold IRAS sources over the
 45-200 um range.  For a subset of these sources, those which
 are relatively bright at 25 um, we will also make full spectral
 scans with the SWS grating.

 Our sample has been selected to represent the earliest stages
 of low-mass star formation. These observations, combined with
 ground-based submillimetre data, will allow the overall spectral
 energy distribution to be measured, the masses and temperatures
 of the cores to be found, and a coherent evolutionary picture of
 early pre-main-sequence evolution to be developed.