Abstract This paper offers a model to explain the general observation that lexical items are more often borrowed from a higher status language into a lower status one, than visa versa. Material from Lahore, Pakistan, shows that in casual speech among plurilinguals codeswitching is the norm. In formal contexts, in which there is attention to proper language, educated speakers filter out features which are not part of the standard language. Constraints on language and education in the hierarchical social structure withhold from most speakers of the lower status languages the knowledge necessary to evaluate their own speech in this way, thus allowing features of other languages to become established in their language.