This article presents the outcomes of a project, which aimed to develop the use of questioning in one teacher's practice using a professional development intervention termed 'clinical supervision'. As well as being a project which adopted an action research approach, this use of clinical supervision is, we argue, a form of professional collaborative support between more- and less-experienced colleagues, akin to the kinds of relationships typical of collaborative action research. Questioning, as a common teaching technique second only to lecturing, is evidenced to be a powerful teaching strategy when used competently. Yet, many teachers struggle to do so by spontaneously asking unplanned questions during a lesson, over-using lower-order questions or even furnishing the answers themselves before waiting for student responses. The current study thus aimed to examine the routine pre-intervention questioning strategies used by the participating teacher and then document the outcomes of the clinical supervision intervention that targeted the development of her questioning skills. Findings indicated that the teacher's pre-intervention use of questioning was typical of the kinds of errors that some teachers make as evidenced in existing literature; while post-intervention findings revealed notable improvement in the teacher's practice of the targeted questioning skills.