Inclusive education has become an international education issue emerging in many developing countries over the last decade. As a developed city, Hong Kong has its own inclusive policies and first implemented inclusive education more than 15 years ago. Although a large amount of funding is injected into this area in Hong Kong each year, many researchers still comment that the inclusion in Hong Kong is far from satisfactory. As teachers are the frontline service providers and commonly recognized as key agents that lead to successful inclusion, their attitudes towards inclusive education are important and should be examined. The present study focused on Hong Kong secondary school teachers' attitudes towards inclusion as well as factors affecting their attitudes in order to draw a clearer picture of the current situation of inclusive education in Hong Kong. Furthermore, this study aims to explore teachers' difficulties in teaching students with special educational needs (SEN) as well as levels of support from the government in the implementation of inclusive education in Hong Kong. In order to investigate this topic, mixed-method research was carried out in this study, applying a quantitative approach by using questionnaires and a qualitative approach through interviews. One hundred and fifty Hong Kong secondary school teachers I responded to a survey in the questionnaire-filling phase while 12 teachers participated in the interview sessions, during which two group interviews and four individual interviews were held. It was interesting to discover that on one hand, the teachers acknowledged the right of students with SEN to be included in regular classes, but on the other, they considered that inclusive education presented many challenges. The study concluded that most of the participants had relatively slightly unfavourable attitudes towards both the general concept of inclusive education and its implementation in Hong Kong. Five factors were identified that affected these attitudes: (1) SEN knowledge and training; (2) availability of personnel and material support; (3) type of disability; (4) severity of disability and (5) inclusive experience. The difficulties of teaching inclusive classes in Hong Kong secondary schools were also revealed in this study. They were: heavy workload; large class size; insufficient support; insufficient training; disciplinary problems and stress from the examination culture. Besides, the participants' concerns about the government's inclusive policies and planning were also mentioned. The teachers also revealed that there were instances of the inappropriate use of inclusive education funding in their schools. In addition, two special phenomena regarding inclusive education in Hong Kong were discovered and they were named 'Killing school effect' and 'Tricky inclusion'. Recommendations are outlined for various stakeholders including education officials, school leaders, special need educators, and teacher training institutions; recommendations are also made for future research in Hong Kong in the field of inclusive education.