  We present the first identification of large-scale structures (LSS) at z $<
1.1$ in the Cosmic Evolution Survey (COSMOS). The structures are identified
from adaptive smoothing of galaxy counts in the pseudo-3d space
($\alpha,\delta$,z) using the COSMOS photometric redshift catalog. The
technique is tested on a simulation including galaxies distributed in model
clusters and a field galaxy population -- recovering structures on all scales
from 1 to 20\arcmin without {\it a priori} assumptions for the structure size
or density profile. Our procedure makes {\bf no} {\it a priori} selection on
galaxy spectral energy distribution (SED, for example the Red Sequence),
enabling an unbiased investigation of environmental effects on galaxy
evolution. The COSMOS photometric redshift catalog yields a sample of
$1.5\times10^5$ galaxies with redshift accuracy, $\Delta z_{FWHM}/(1+z) \leq
0.1$ at z $< 1.1$ down to I$_{AB} \leq 25$ mag. Using this sample of galaxies,
we identify 42 large-scale structures and clusters. abstract truncated for
astroph 25 line limit -- see preprint
