The purpose of this study was to investigate the impact of class size on the learning and teaching of English in an intensive pre-university program. Four 'larger' and four 'smaller' sized classes were created, and each class was populated with a mix of students in terms of achievement and motivation. Tutors were assigned to both large and small classes, and tutor quality was controlled for qualifications, experience, and demonstrated effectiveness. When student grades were analysed at the end of the course, no significant differences in student achievement were found in overall, end-of-course grades. However, for students at the elementary language level, class size had an impact on their success. In addition, it was found that tutors as well as students indicated a strong preference for smaller-sized classes at both elementary and intermediate language levels. The study adds insights from a rapidly evolving international higher education context to the existing body of research into the impact of class size on students and teachers.