TREL is a professional learning network in which participants engage in collaborative and reflective dialogue concerning how best to apply teacher know-how about research learned and taught in universities to their school-based practices to help them generate critical inquiry, reflection, and continuous professional self-development. TREL brings together partners from eight higher education institutions (HEIs) and practitioners from three upper-secondary schools in the Nordic-Baltic region. Partners in the TREL project are committed to using a variety of research-driven activities and methods to promote teacher professional development and support for teachers’ research literacy, which can be described as the knowledge and skills pre-service and in-service teachers need to successfully undertake research. The TREL project aims to identify best practices in the Nordic-Baltic educational context and seeks to organize workshops, classroom observations, and research projects, as well as publish a handbook of best practices for building up teacher research literacy. TREL's aim is to benefit teachers, schools, and educational institutions by contributing to the development of research skills/literacy in teacher education and aiding teachers in transforming the knowledge thus gained into advanced research and professional development competence. Developing teacher research literacy facilitates teachers' active learning, critical reflection, and problem-solving, and promotes an awareness of the potential benefits of research-oriented classrooms and schools.