The instant invention is a heat activated adhesive composition comprising an ultra-high solid polyurethane dispersion. The ultra-high solid polyurethane dispersion comprises (1) a first component comprising a first polyurethane prepolymer comprising the reaction product of a polyol and polyisocyanate, (2) a second component comprising a media phase selected from the group consisting of a second polyurethane prepolymer emulsion, a low solid content polyurethane dispersion, a seed latex, and combinations thereof; and (3) optionally a chain extender. The ultra-high solid polyurethane dispersion has at least a solid content of at least 60 percent by weight of solid content, based on the total weight of the ultra-high solid polyurethane dispersion, and a viscosity of less than 5000 cps at 20 rpm at 21° C. using spindle #4 with Brookfield viscometer.