Disclosed herein is a polymeric paint additive that increases the open time and the flow and leveling of paint compositions, as well as, maintaining/improving paint film properties such as scrub resistance, water sensitivity, surfactant leaching and stain removal. The polymeric open time additive preferably has a high glass transition temperature, e.g., above 100° C., as determined by the well-known Fox's equation, and molecular weight of less than 20,000 Daltons (number average molecular weight). The particle size of the inventive polymeric open time additive is in the range of about 130 nm to about 230 nm (volume average), prior to being dissolved in a basic solution, such as an aqueous architectural composition.