Purpose: This paper presents findings of a classroom-based research project that investigated the use of plurilingual tasks in the English as a foreign language (EFL) teaching context. The project aimed at examining: (1) the impact of the use of plurilingual tasks on language learning processes and learners' identity construction; and (2) the pedagogical gaps that need to be addressed in language teacher education. This paper focuses specifically on the first research question. Design/methodology: The project was carried out in the form of five case studies conducted in four primary schools and one secondary school in Germany. Research data were collected via a variety of ethnographic research instruments namely classroom observations and field notes, video recording of school lessons, in-depth interviews with teachers, teachers' reflective journals, anonymous questionnaires, and learner focus group interviews. Research findings: Drawing upon Darvin and Norton's (2015) concept of investment, the paper discusses research findings indicating that the use of plurilingual tasks had a positive impact on the EFL learners' investment in language learning activities. Originality/Value: The main implication that can be drawn from the findings is that the effective integration of plurilingual-inspired pedagogies in the foreign language classroom does not involve necessarily a drastic reformulation of learning goals and teaching procedures, but mainly a change in teachers' attitudes towards plurilingualism in the classroom.