Teacher expectations can be defined as the beliefs that teachers hold about what their students are capable of achieving. Teacher expectations are important to study because they influence teacher practice and subsequently student academic and psychological outcomes (such as motivation and self-belief). For example, if teachers believe that all their students can achieve at high levels, they are likely to provide learning opportunities and supports that enable their students to be successful. Teacher expectations have been studied for the past 50 years since Rosenthal and Jacobson’s experimental study, Pygmalion, showed that when teacher expectations were raised for some students, they subsequently performed at higher levels. This initial teacher expectation experiment led researchers to study how teachers differentiated in their behaviours towards high and low achievers, what student characteristics influenced teachers’ expectations, what the effects were on student outcomes when teachers had high or low expectations for particular students, and what behaviours students reported that teachers displayed towards high and low achievers. These areas formed the key areas of subsequent research in the field. However, researchers recognised early on that not all teachers differentiated in their behaviours towards high and low achievers and that not all formed their expectations in line with common stereotypes (e.g. that boys are better at mathematics than girls). This led to the identification of specific types of teachers who either exacerbated the gaps between high and low achievers or who increased the success of all students. However, although much is now known about teacher expectations and teacher expectation effects, few studies have experimentally endeavoured to change teachers’ expectations and support teachers to implement high expectation practices. However, the few that have worked alongside teachers to raise their expectations have shown promising results for students’ educational outcomes.