It is commonly believed that small class teaching can greatly enhance student learning because the individual needs of each student can be better addressed, the students can learn more through more innovative and flexible teaching methods and the students have more time to interact with each other and to gain feedback from their teachers. Although studies have shown that students benefit from small class teaching, they have failed to identify the benefits as the natural consequences of a simple reduction in class size. As increasing numbers of researchers argue that professional development in small class teaching is more important than a simple reduction in class size, it is timely to determine the factors that affect teachers’ participation in small class teaching professional development programmes and their use of small class teaching after participation in these programmes. This study explored teachers’ concerns about or obstacles to applying their knowledge from professional development programmes to their teaching. Teachers who had participated in a government-funded professional development programme were invited to complete an end-of-programme questionnaire, and 160 valid questionnaires were collected. The initial findings indicate that workplace factors were the most common factors in the implementation of small class teaching.