Two general principles of sexual differentiation emerge from previous sociolinguistic studies: that men use a higher frequency of nonstandard forms than women in stable situations, and that women are generally the innovators in linguistic change. It is not clear whether these two tendencies can be unified, or how differences between the sexes can account for the observed patterns of linguistic change. The extensive interaction between sex and other social factors raises the issue as to whether the curvilinear social class pattern associated with linguistic change is the product of a rejection of female-dominated changes by lower-class males. Multivariate analysis of data from the Philadelphia Project on Linguistic Change and Variation indicates that sexual differentiation is independent of social class at the beginning of a change, but that interaction develops gradually as social awareness of the change increases. It is proposed that sexual differentiation of language is generated by two distinct processes: (1) for all social classes, the asymmetric context of language learning leads to an initial acceleration of female-dominated changes and retardation of male-dominated changes; (2) women lead men in the rejection of linguistic changes as they are recognized by the speech community, a differentiation that is maximal for the second highest status group.