This talk addresses the question of what drives formal linguistic change and it proposes that at least some cases of (language-internal) formal change may result from (language-external) pragmatic and semantic borrowing. More specifically, I propose that the following chain of events is unexceptional: (1) speakers of a language may borrow the meaning -- semantic or pragmatic -- associated with some form in a contact language/dialect and associate it with some form found to be analogous in their own language, (2) since meaning dictates word-choice and frequency, the new meaning may affect the data that the next generation of speakers hears and on which they base their construction of the grammar of the language; the more different the new database is from the old, the more different the new generation's grammar is likely to be, i.e. the more formal change will have occurred.