We present an experimental study of the rheology of polystyrene latices phase separated by dissolved dextran polymer. Our phase‐transition experiments are guided by a statistical mechanical theory which predicts this phase transition and the densities of each phase. Measurements of the steady shear viscosity and the linear viscoelastic response at fixed polymer concentration well into the two‐phase region define the dependence on latex volume fraction. Viscoelasticproperties of the separated dense phase near the phase boundary (at equilibrium) are also presented. A low frequency plateau in G′ and an apparent yield stress appear for samples in the two‐phase region and increase exponentially with volume fraction of particles.