Like many other sub-fields of sociolinguistics, two seemingly unbridgeable gaps exist in the sociolinguistic study of multilingualism and identity in urban settings. First, existing studies tend to examine Western and/or English-speaking societies only; and moreover, they do so by using either quantitative or qualitative methods and rarely considering both approaches. As a result, relevant theories have been developed without taking into consideration cases outside these sites using a more comprehensive methodological approach. This chapter presents a case study of urban multilingualism in Ningbo in Eastern China to demonstrate how investigations of non-Western/non-English multilingual settings incorporating interdisciplinary methodologies can help to validate, challenge and, more importantly, expand our understanding of the sociolinguistics of multilingual identity, both theoretically and methodologically. Informed by a variationist approach and mixed-methods designs, the case study not only presents the multilingual sociolinguistic reality of Ningbo, but also shows how an interdisciplinary perspective enriches the field of sociolinguistics.