Previous studies in both educational and sport settings have examined the relationship between teachers' and coaches' expectations and behaviors towards students and athletes. The purpose of the present study was to extend this line of research by examining the effects of teachers' expectations about students' motivation on the frequency of controlling and autonomy-supportive behaviors. Following the assessment of teachers' expectations about students' motivation and the assessment of students self-determined motivation at the end of the first lesson, the interactions between PE teachers from 9 classes and 172 students were videotaped and systematically coded during the 6 following gymnastics courses. Analyses revealed that (1) teachers' expectations were not related to students' initial self-determined motivation, (2) overall teachers interacted less frequently with students that they expected to be more motivated, and (3) teachers were much more controlling with students that they believed to be not motivated. The results are discussed in terms of the consequences of this differentiated treatment for students' autonomous motivation.