Abstract: Aqueous dispersions of urethane polymers and vinyl polymers (e.g., acrylics) are disclosed that provide water-based coating compositions with good adhesion following humidity exposure. The dispersion is predominately urethane, and the polyurethane is made from a first and a second polyisocyanate, the first polyisocyanate having at least one open carbon chain greater than six carbon atoms in length between two isocyanate groups, preferably at least eight carbon atoms in length. The vinyl monomers are polymerized in the presence of the aqueously dispersed polyurethane.