  Initial conditions for star formation in clusters are estimated for
protostars whose masses follow the initial mass function (IMF) from 0.05 to 10
solar masses. Star-forming infall is assumed equally likely to stop at any
moment, due to gas dispersal dominated by stellar feedback. For spherical
infall, the typical initial condensation must have a steep density gradient, as
in low-mass cores, surrounded by a shallower gradient, as in the clumps around
cores. These properties match observed column densities in cluster-forming
regions when the mean infall stopping time is 0.05 Myr and the accretion
efficiency is 0.5. The infall duration increases with final protostar mass,
from 0.01 to 0.3 Myr, and the mass accretion rate increases from 3 to 300 x
10^(-6) solar masses/yr. The typical spherical accretion luminosity is ~5 solar
luminosities, reducing the luminosity problem to a factor ~3. The initial
condensation density gradient changes from steep to shallow at radius 0.04 pc,
enclosing 0.9 solar masses, with mean column density 2 x 10^(22) cm^(-2), and
with effective central temperature 16 K. These initial conditions are denser
and warmer than those for isolated star formation.
