This study aims at understanding teacher educators' professional development (TEPD) from the unique perspective of a group of educators who are regularly involved in planning, managing and implementing varied professional development programs for teacher educators, at the MOFET Institute in Israel. Working theories were derived from the participants' statements as to the preferable course of TEPD. These evolved around three mental images of the professionally well-developed teacher educator: the model pedagogue; the reflective, self-studying practitioner; and the developer of professional identities. These three working theories were followed by a fourth one relating to TEPD from the teacher educators' own point of view.