Globalisation has resulted in European families that have a variety of home languages, leading to the need for heritage language learning (HLL). The purpose of HLL is to ensure that in addition to learning the language of their schools, children with migrant backgrounds also maintain their heritage language (HL). Besides the 'regular' teaching, in many countries, there are usually voluntary, extra-curricular maintenance courses available for migrant children. The purpose of our study was to investigate the impact that HL teachers working in Finnish schools have on the process of learning HLs. The data were collected using a Likert-scale questionnaire (N = 25) and semi-structured interviews (N = 15) with HL teachers representing 24 different languages. Principal Component Analysis (PCA) was conducted to check the survey construct validity. The statistical and qualitative analysis of the data indicated that HL teachers act as multilingual identity supporter, that is that they showed understanding of their students' multilingualism and were convinced about the positive impact of HL for students' future lives. Our study also reported on the challenges teachers face in the classroom.