This chapter investigates the relationship between language, ethnicity, national identity and party support in Taiwan. It tries to answer three questions: What are linguistic identities? What is the place of local Taiwanese languages, especially Hoklo, in ethnic and national identities in Taiwan? Does the use of Hoklo matter for electoral outcomes? Most of the analysis is based on large-N data from the Taiwan Social Change Survey (TSCS) on National Identity, conducted by Academia Sinica's Institute of Sociology in 2003, at a time when culture politics and discourses on the legal status of minority languages were at their peak in Taiwan. The Taiwanese have lived under different language regimes, and Taiwanese society has experienced a number of language shifts over the past centuries. The chapter inquires whether language use at home matters for national identity and electoral outcomes, with a particular emphasis on the Hoklo group.