This article describes phases of post-lesson reflective dialogues that were enacted by secondary school mathematics student teachers with their peers. Five pairs of student teachers on 12 weeks of teaching practice provided data through lesson assessments, post-lesson reflective dialogues, and end-of-teaching-practice reflective interviews. A cognitive theory of collaborative reflection with a peer that encapsulates phase characteristics of a post-lesson reflective dialogue is proposed. Dialogue at each of the phases of the theory may not easily change student teachers' conceptions of teaching, but could provide a platform and structure for reviewing, modifying, or even maintaining teaching cognitions. While the older and more familiar "apprenticeship" models are based on an expert teacher coaching a novice student teacher instructional skills, this fresh "social" model is based on novice student teachers and their peers coaching each other teaching skills. An important implication of this observation is that current discourse on strategies for improving the quality of student teaching may move towards a consideration for a fresh school attachment model.