Abstract: This paper is a review of research that has been conducted on polymer modified binders over the last three decades. Polymer modification of asphalt binders has increasingly become the norm in designing optimally performing pavements, particularly in the United States, Canada, Europe and Australia. Specific polymers that have been used include rubber, SBR, SBS and Elvaloy®. Specifications have been designed and pre-existing ones modified to capture the rheological properties of polymer modified binders. The elastic recovery test is good at determining the presence of polymers in an asphalt binder, but is less successful at predicting field performance of the pavement.