This chapter focuses on teacher agency regarding plurilingualism as exhibited at a Finnish heritage language school in the United States. Heritage languages (HLs) are minority languages that usually exist within macro-systems of societal language policies that marginalize the HL as compared to the dominant language. This situation is especially pronounced in the United States, where English-only practices and policies in education run counter to the plurilingual realities of the nation’s large HL-speaking population (Hopkins, 2016; Kircher & Kutlu, 2023; Wiley & García, 2016).

HL schools have been established by immigrant communities to ensure the transmission of the HL to the next generation as a deliberate countermeasure to the influence of the dominant language. HL students are often directed by their teachers to only speak the HL. However, it is not realistic to expect that HL students, who are multilingual by definition, behave as monolinguals even within the walls of the HL school. Moreover, plurilingualism, or the competence in multiple languages and the tendency to value other languages and language varieties (European Council definition as cited by García & Otheguy, 2020), is both a rich resource for global engagement and an important part of an individual’s identity.

Teachers at HL schools must negotiate instructional and language policy decisions within these multilayered ideological spaces, which make them an interesting research context for examining language teacher agency. Teacher agency, which can be defined as the “freedom to accomplish what teachers see as valued and valuable tasks” (Molla & Nolan, 2020, p. 69), served as the 286main theoretical lens for this study. Li and Shen (2024) argue that research has so far focused on individuals’ agency around language planning in more traditional language acquisition contexts, i.e., public schools, and that it has yet to be closely examined in HL educational contexts. This chapter responds to this gap by examining Finnish HL teachers’ enactment of their agency regarding plurilingualism in an HL school. The research question guiding the study was, How do Finnish heritage language teachers enact their agency while negotiating plurilingualism within an HL school located in the United States?