In this study, we investigate whether preposition stranding, a stereotypical non-standard feature of North American French, results from convergence with English, and the role of bilingual code-switchers in its adoption and diffusion. Establishing strict criteria for the validation of contact-induced change, we make use of the comparative variationist framework, first to situate stranding with respect to the other options for preposition placement with which it coexists in the host language grammar, and then to confront the variable constraints on stranding across source and host languages, contact and pre-contact stages of the host language, mainstream and "bilingual" varieties of the source language, and copious and sparse code-switchers. Detailed comparison with a superficially similar pre-existing native language construction also enables us to assess the possibility of a language-internal model for preposition stranding. Systematic quantitative analyses turned up several lines of evidence militating against the interpretation of convergence. Most compelling are the findings that the conditions giving rise to stranding in French are the same as those operating to produce the native strategy, while none of them are operative in the presumed source. Explicit comparison of copious vs. sparse code-switchers revealed no difference between them, refuting claims that the former are agents of convergence. Results confirm that surface similarities may mask deeper differences, a crucial finding for the study of contact-induced change.