This paper examines data concerning the acquisition of Spanish second language copula choice in terms of similarities to data collected in studies of language change, using the variables of frame of reference and susceptibility to change, which have been proved useful for analyzing the process of the extension of 'estar' to new contexts from a sociolinguistic perspective. The application of these variables to second language acquisition data enables to study the hypothesized mirror-image relationship between the processes of language loss and language acquisition.