The number of immigrant students in Finland is increasing; thus, this qualitative case study investigates ways of providing targeted support measures for recently arrived Finnish language learners (RAFLLs) in Finnish lower secondary education. Focusing on linguistic responsiveness, the teaching arrangements and support measures are examined not only from a teacher perspective but also from the perspectives of municipality- and national-level actors by utilizing ecological systems theory. The findings revealed two themes, sustainability and holistic linguistic responsiveness, that reflect the core issues of the current challenges related to organizing teaching and support measures for RAFLLs. Sustainable support measures should be developed on and between all ecosystemic levels. Furthermore, measures for supporting RAFLLs must be developed with an all-encompassing linguistically responsive approach (LRA). The development processes require a more coherent dialogue between the schools, the municipalities, and the national-level actors.