This paper reports on a research study of 28 literacy teacher educators (LTE) in four countries: Canada, the USA, England and Australia. It identifies three main forms of professional development: informal, formal and communities of practice and four spheres of knowledge: research; pedagogy of higher education; literacy and literacy teaching; and current school district and government initiatives. The study reveals the sheer scale of knowledge required to be an effective LTE and demonstrates how participants used the three forms of professional development to enhance their knowledge in each sphere. It concludes that the professional development of teacher educators is not conducted systematically; rather, it is quite ad hoc with much of it occurring through learning while doing. All had to construct their own programmes for professional development, which added yet another layer to their responsibilities.