Based on an inspection of sessions with intellectually impaired and non-impaired clients, five conversational practices are identified by which a cognitive behaviour psychotherapist may keep the session "on-track" in the face of possible deviation. Close inspection of audio- and video-recordings reveals a gradient of therapist responses. They range between minimal receipt of what the client has said, even when this would otherwise have warranted expansion, all the way to explicit active topic shift which takes a more directive role. The operation of these topic-management practices is explained using Conversation Analysis, and their therapeutic utility and possible dangers are outlined. The article ends with a brief sketch of the tension between an "outsider's" Conversation-Analysis perspective on the organisation of therapy talk, and a therapist's, "insider's", view of the meanings and intentions of what participants say.