  The Red-Sequence Cluster Survey (RCS) is a 100 deg^2 galaxy cluster survey
designed to provide a large sample of optically selected clusters of galaxies
with redshifts 0.1<z<1.4. The survey data are also useful for a variety of
lensing studies. Several strong lensing clusters have been discovered so far,
and follow up observations are underway. In these proceedings we present some
of the first results of a weak lensing analysis based on ~24 deg^2 of data. We
have detected the lensing signal induced by intervening large scale structure
(cosmic shear) at high significance, and find \sigma_8=0.81^{+0.14}_{-0.19}
(95% confidence; for a LCDM cosmology. Another application of these data is the
study of the average properties of dark matter halos surrounding galaxies. We
study the lensing signal from intermediate redshift galaxies with 19.5<R_C<21
using a parametrized mass model for the galaxy mass distribution. The analysis
yields a mass weighted velocity dispersion of 111+-5 km/s. In addition we have
constrained for the first time the extent of dark matter halos, and find a
robust upper limit for the truncation parameter s<470 h^{-1} kpc (99.7%
confidence). The biasing properties of these galaxies as a function of scale
are also studied. The RCS data allow us to measure the ratio of the bias
parameter b and the galaxy-mass cross-correlation coefficient r. The results
are consistent with a scale-independent value of b/r, for which we find
b/r=1.05^{+0.12}_{-0.10}.
