The studies considered in this review of recent research on teachers' professional identity can be divided into three categories: (1) studies in which the focus was on teachers' professional identity formation, (2) studies in which the focus was on the identification of characteristics of teachers' professional identity, and (3) studies in which professional identity was (re)presented by teachers' stories. In the studies reviewed, the concept of professional identity was defined differently or not defined at all. Four essential features of teachers' professional identity could be derived from the studies. Many of the reviewed studies appeared to be studies on teachers' personal practical knowledge. However, in only a few studies was the relationship between this knowledge and professional identity made explicit. It is argued that, in future research on teachers' professional identity, more attention needs to be paid to the relationship between relevant concepts like 'self' and 'identity', the role of the context in professional identity formation, what counts as 'professional' in professional identity, and research perspectives other than the cognitive one that may also play a role in designing research on teachers' professional identity.