In collaboration with Yao Yao, I am examining the development of a sound change in Shanghainese that is influenced by increasing bilingualism in Mandarin. This sound change (raising and diphthongization of mid front vowels) is noteworthy because it is resulting in a rare reversal of a previous vowel merger. The project is geared toward examining the interaction of general bilingualism, code-switching, and cognation in the propagation of this sound change in modern-day Shanghai. We reported results of the first stage of this project in a recent Language paper (Yao & Chang, 2016).