The principle of educating students with special educational needs in the least restrictive settings renders a rapid growth of the population of students with autism spectrum disorders (ASD) in ordinary schools in the last decade. This change has caused a concern to teachers in ordinary schools. To equip teachers in ordinary schools with the knowledge and skills in dealing with special edu-cational needs, different tiers of professional development programs have been developed. The problem is that these programs are mainly short-term and direct top-down transmission in nature. The lack of opportunity to try out the newly acquired knowledge and skills in real environments cannot give sufficient confi-dence to teachers to work with students with ASD independently. This chapter discusses the effectiveness of a current professional development (PD) program for teachers of students with ASD in Hong Kong SAR. A collaborative mode of PD is recommended that can assist teachers to gain hands-on experience in a field-based training program.