  We present results from 1078 high resolution spectra of 990 stars in the
young open cluster NGC 2264, obtained with the Hectochelle multiobject echelle
spectrograph on the 6.5m MMT. We confirm 471 stars as members, based on their
radial velocity and/or H-alpha emission. The radial velocity distribution of
cluster members is non-Gaussian with a dispersion of approx 3.5 km/s. We find a
substantial north-south velocity gradient and spatially coherent structure
inthe radial velocity distribution, similar to that seen in the molecular gas
in the region. Our results suggest that there are at least three
distinguishable subclusters in NGC 2264, correlated with similar structure seen
in 13CO emission, which is likely to be a remnant of initial structure in this
very young cluster. We propose that this substructure is the result of
gravitational amplification of initial inhomogeneities during overall collapse
to a filamentary distribution of gas and stars, as found in simulations by
Burkert & Hartman (2004).
