A study investigated the benefits to three practicing teachers of the experience of being observed by preservice teacher trainees. Information was drawn from teacher journal entries concerning this experience, observations by the student teachers, and conversation among teachers and between teachers and preservice observers. Specifically, the investigation considered: (1) how the presence of student observers affected teaching behavior and decision-making; (2) teachers' discoveries about their own approaches to teaching through this experience; and (3) how being observed affected teachers' views of themselves as language teachers. The teachers being observed were instructors of English for special purposes and English for academic purposes in a Hong Kong higher education institution. Results are discussed and illustrated by teacher comments. Teachers noted both benefits and limitations to learning from observation by student teachers. It is concluded that for teachers to take advantages of student observation as a tool for their own professional development, some observation tasks should require documentation of causal relationships in classroom events; teachers should help develop some of the observation protocols; teachers should keep journals of the experience; discussion among colleagues also being observed should be promoted; observers be discouraged from making evaluative comments; followup discussion between teacher and observer be included. (MSE)