Supervising masters and doctoral dissertations is a key function of teaching in higher education and giving written feedback on draft sections is an essential component of this function. However, the specific types of response that supervisors give to their dissertation students' written work have received limited research interest to date. The present study drew on an academic discourse community perspective in examining feedback comments on draft sections of dissertations across three disciplinary areas. It investigated which aspects of writing the comments focused on and how the comments were formulated linguistically, and developed descriptive frameworks that may be of value to supervisors wishing to reflect on their practice. Findings are discussed in relation to supervisors' perspectives, academic discourse community expectations and norms of supervisory communication.