This paper studies the roles of local identity and language attitude in language change by examining Tianjin Chinese tone sandhi in apparent time (90 speakers, sociolinguistic interviews, born 1932-1996). Previous studies on Tianjin Chinese indicated that some dialect features were decreasing in frequency over time (Gao and Lu 2003, Gu and Liu 2003, X. Wang 2017), but some other dialect features were increasing (Shi and Wang 2004, X. Wang 2017). Why are local features of Tianjin dialect changing in different directions under the same social and linguistic conditions? We propose that the influence of Standard Chinese (SC) and negative attitude to Tianjin dialect make the stereotyped local features decrease, while the desire to keep local identity, especially when facing a large number of migrants, makes the unmarked local features increase. This is in line with Labov’s (1972) study of Martha’s Vineyard, whereby traditional local features may come to index resistance to standardization and to the incursion of new people into the speech community.