Abstract: Aqueous dispersions of urethane polymers and vinyl polymers (e.g., acrylics) that provide water-based coating compositions with good adhesion following humidity exposure are further improved by providing branching chain extension of the polyurethane. The branched polymers provide improved metallic pigment orientation in coating compositions. Branching is provided by the use of chain extending agents selected from polyamines having at least three primary amine groups and polyols having at least three hydroxyl groups. The vinyl monomers are polymerized in the presence of the aqueously dispersed polyurethane.