The call for digitalisation in compulsory and upper secondary schools implies the need for teachers to pursue professional development. Here, teachers' self-understanding may influence how they use, relate to and learn about digital technologies. The purpose of this article is to explore how a teacher's self-understanding influences his professional development activities and, in turn, is influenced by his learning. The case study focuses on one upper secondary school teacher's endeavour to enact digital technologies and find suitable strategies for professional learning. This teacher and a researcher formed a reflective research partnership to explore how, and whether, the teacher's self-understanding and professional learning strategies influenced each other. The findings show how his "task perception" changed over time from an emphasis on teaching to a greater emphasis on improvement, supporting colleagues in their learning and contributing to the professionalisation of the teaching community. This influenced his adoption of a self-directed learning strategy.