Commonsense reasoning says that quality teacher education relies on quality teacher educators. Yet, there is minimal attention to what teacher educators should know and be able to do. Unquestionably, teacher educators cannot teach what they do not know; but what "should" they know, and should they be prepared? This study of 293 teacher educators investigated the following: What do current teacher educators consider to be the foundation elements of their practice? How do they evaluate their own preparation in these areas? How can their experiences inform the preparation of teacher educators? We use Cochran-Smith and Lytle's theorizing about "relationships of knowledge and practice" to understand knowledge essential to teacher educating (a term we use to differentiate teaching teachers from teaching students). Our findings reveal that practicing teacher educators often feel unprepared to assume their role but can offer helpful insight into how we should think deliberately about quality teacher educator preparation.