In this study, we examine a real-life case from a Finnish early primary school classroom and elaborate how the teacher and student(s) together create space for heterogeneous ways of being in the classroom that support their social and emotional competences and well-being. Our study offers conceptual tools and knowledge to support teachers in harnessing heterogeneity in classrooms – to embrace the ‘stranger’ in both the student and the teacher – to develop pedagogical interaction in challenging classroom contexts. Based on the study, we propose a map for embracing challenging situations in heterogeneous classrooms through a transformative teaching stance. Central dimensions of the map are (i) the dialectical nature of fostering learning in an institutional context, (ii) its embodiment in co-regulative processes in students and teachers as experiences of ambivalence and edge-emotions and (iii) sources of support for teachers to sustain a transformative teaching stance. Implications for supporting SEL with a view on teachers’ well-being are discussed.