This chapter explores the processes of differentiation “between” teachers who work in countries with different professional regulatory models. It provides a novel approach to analysing the influence of different performance-based accountability (PBA) policy approaches on the professionalism and work of teachers. To do this, the chapter presents the main results of a systematic literature review in which the recent literature on teacher professionalism and PBA is examined. This is retrieved from two databases: SCOPUS and Web of Science (WoS). The sample of articles of this study includes a total of 101 pieces of research. The chapter highlights the pivotal role of specific regulatory models in the teaching profession, and the role PBA plays in them. These regulations are closely connected to different administrative traditions, and facilitate the emergence of differentiation processes between professional systems. Specifically, the chapter shows how these regulations influence the very nature of the teaching profession and of teachers’ work itself; it explores how they have developed, and the inner tensions that affect them.