  We present new, high-quality multicolor observations of four recently
discovered contact binaries: 1SWASP J064501.21+342154.9, 1SWASP
J155822.10-025604.8, 1SWASP J212808.86+151622.0, and UCAC4 436-062932, and
analyze their light curves to determine orbital and physical parameters using
the modeling program of G. Djura\v{s}evi\'c. In the absence of spectroscopic
observations, the effective temperatures of the brighter components are
estimated from the color indices, and the mass ratios are determined with the
q-search method. The analysis shows that all four systems are W UMa type
binaries in shallow contact configurations, consisting of late-type
main-sequence primaries and evolved secondaries with active surface regions
(dark or bright spots) resulting from magnetic activity or ongoing transfer of
thermal energy between the components. We compare the derived orbital and
stellar parameters for these four variables with a large sample of previously
analyzed W UMa stars and find that our results fit it well.
