ABSTRACT
The author proposed the Theory of Speech Community and the Theory of Linguistic Urbanization to account for the complexity of sociolinguistic indexicality, the former dealing with the 'ranges' issue and the latter with its dynamic aspect. The most fundamental linguistic changes are the restructuring and reorganization of speech communities due to the unprecedented scale and magnitude of mass migration and social mobility. The findings of sociolinguistic stratification and sociolinguistic interaction, Chinese sociolinguists attempted to integrate the two into an interaction-based sociolinguistic system. The relatively independent and rapid development of Chinese sociolinguistics in the twenty-first century is evidently contextualized in the fast-paced and far-reaching changes of contemporary Chinese society. According to Theory of Speech Community (TSC), the nature of a constraint pattern is 'the shared evaluation of linguistic variables' and 'uniformity of abstract patterns of variation', which are two defining features of a speech community. A set of constraints for a variable makes up a constraint pattern.
