Abstract: Modified asphalt compositions are described which comprise(A) asphalt, and(B) a minor amount, sufficient to reduce or retard degradation of the asphalt in service, of at least one carboxy ester-containing interpolymer derived from(B-1) at least one olefin monomer, and(B-2) at least one alpha, beta-unsaturated carboxylic acid or derivative thereof, said interpolymer having (1) pendant carboxylic acid ester groups derived from the esterification of the carboxy groups of the interpolymer with at least one alcohol containing at least about 4 carbon atoms.Generally, the modified asphalt composition will contain from about 0.01 to about 10% by weight, based on the weight of the asphalt, of the ester of a carboxy interpolymer as defined. The modified asphalt compositions of the present invention are useful in roofing applications and in preparing aggregate-containing asphalt concretes which can be employed as paving compositions.