This talk reviews the most recent results from the B-meson factories,
BABAR and Belle, to constrain the angle beta of the unitarity triangle.
The parameter sin2beta is obtained from measurements of CP violation in 
the interference between decay with and without mixing in 
tree-level-mediated quark decays b -> c cbar s.
The fourfold ambiguity on beta can be reduced to a twofold ambiguity
by determining the parameter cos2beta. The sign of cos2beta provides 
important information on possible New Physics contributions in neutral
B-meson mixing. Several methods have been proposed in the literature
to measure cos2b and the current experimental status is reviewed.