This article reports on the results of a research project in which 18 teacher educators in three countries—Australia, The Netherlands, and United Kingdom—were interviewed about their experiences of working in the so-called "third space" between schools and universities, particularly in relation to the practicum, or field supervision. Most teacher educators have previously worked as teachers in schools or other educational settings, and when they become teacher educators in universities, they are often involved in the supervision or mentoring of preservice teachers in the field. The research reported in this article examined how university-based teacher educators manage the challenges inherent in working with mentor/cooperating teachers after having been or when still practicing as teachers in schools. Findings from the study showed that for teacher educators, working in the third space involves managing shifting identities between teacher and teacher educator, responding to changing perspectives on learning and teaching, and negotiating sometimes finely balanced and difficult relationships.