This paper presents the research results on the issue of primary school teachers' self-perceived professional competence in supporting pupils whose mother tongue differs from the language of instruction. The aim of the research was to explore teachers' perceptions of their competence and confidence levels while working with multilingual pupils. A mixed-methods approach was employed to collect quantitative data through a questionnaire and qualitative data through interviews with voluntary participants.

The research findings were analysed across three key areas:
1. teachers' experiences in communicating with multilingual pupils,
2. teachers' strategies for adapting learning tasks, and
3. teachers' perceptions of challenges they encounter.

The results showed that teachers perceive themselves to be insecure in comprehensively supporting pupils speaking a different mother tongue in the school environment, despite the fact that teachers manage communication with these pupils in the teaching process. They have moderate confidence in adapting teaching tasks. However, they fail to sufficiently develop communication with the families of these pupils, which reduces family-school cooperation. Findings indicated the need for expanding pre-graduate study and providing of a wider range of professional resources in this area. The discussion confronted the findings with the current state of professional development of primary teachers in this area.

Acknowledgement:
This study was supported by the Slovak Research and Development Agency under the Contract No. APVV-22-0450 and the project KEGA 008UMB-4/2024 Creation of Textbook and Methodological Material for Teaching Slovak Language for Children of Slovaks Living Abroad.

Keywords: Primary education, educational environment, self-efficacy, pupils speaking different mother tongue, teachers' perceptions.