A cosmetic or dermatological composition comprising at least one gradient copolymer comprising at least two different monomers, displaying a mass polydispersity index (Ip) less than or equal to 2.5 and for example, additionally a low composition polydispersity. A cosmetic or dermatological method for make-up or care of keratinous substances, notably the skin of the body or of the face, the nails, the hair and/or the eyelashes, comprising application of a cosmetic composition as defined above on the said substances.