The current study describes the design, implementation, and analysis of a professional development programme using a Lesson Study model to enhance awareness in preschool professionals regarding inclusive education for children with autism spectrum disorder. The mixed method approach included pre- and post-intervention questionnaires, audio-recordings of group seminars, and an interview. The results indicated an increase in autism awareness among the professionals, suggesting that professionals changed their practice as a result of the programme. This was particularly clear regarding making adjustments to the learning environment and taking measures to prevent challenging situations. In addition to describing the implementation of a professional development programme in a preschool, this paper emphasises the importance of appropriate conditions for such initiatives.