  Broadband optical and IR spectral energy distributions are determined for
spectroscopically confirmed z>2 Lyman break objects in the Hubble Deep Field
(HDF). These photometric data are compared to spectral synthesis models which
take into account the effects of metallicity and of internal reddening due to
dust. It is found that, on average, Lyman break objects are shrouded in enough
dust (typically E(B-V)~0.3) to suppress their UV fluxes by a factor of more
than 10. The dust-corrected star formation rate in a typical HDF Lyman break
object is ~60 h^-2 M_sun/yr (q_0=0.5). Furthermore, these objects are dominated
by very young (<~0.2 Gyr, and a median of ~25 Myr) stellar populations,
suggesting that star formation at high redshift is episodic rather than
continuous. Typically, these star formation episodes produce ~10^9 h^-2 M_sun
of stars, or ~1/20 of the stellar mass of a present-day L* galaxy.
