This paper examines how a team of teachers in a Norwegian upper secondary school responds to, negotiates, and evaluates students' writing in and across different disciplines. The purpose is to identify discourse strategies and professional development as the teachers discuss students' texts, and to explore how the teachers develop a shared understanding of how writing relates to students' learning. The findings show how the teachers' discourse reflects an emerging understanding of how writing is both a subject-specific and interdisciplinary skill conducive to learning, but also how institutional traditions and discipline-specific concerns together allow for and constrain teachers' learning.