University-based teacher-education programmes in the USA confront mounting pressure to demonstrate that graduates will have a significant and positive impact on student achievement. Such pressure has forced teacher educators to wrestle with the question of what constitutes compelling evidence that teacher candidates will indeed have such an impact. This paper presents the deliberations and resulting investigation of a team of university faculty members seeking to account for preservice elementary-school teachers' learning and development. It offers a preliminary articulation of a trajectory of learning, and a critique of the tasks and the programmatic experiences from which this trajectory is constructed. (Contains 1 table and 15 notes.)