  NGST offers unprecedented opportunities for charting the `dark ages' beyond
the limits of the deep optical surveys conducted with HST. An equally important
motivation, however, is a detailed physical understanding of the later stages
of cosmic history including the period 2<z<5 when most galaxies are thought to
assemble and undergo dramatic changes in their star formation rate, chemical
content and, ultimately, their morphological characteristics. An important
question we need to resolve is the extent to which established massive systems
might exist at moderate redshifts. In the context of recent observational and
theoretical progress in this area, I review the role NGST could play in this
redshift range taking into account the likely progress made in the next decade
with the new generation of 8-m class ground-based telescopes
