Although children with autism spectrum disorder (ASD) are increasingly being placed within mainstream classes, little is known about the challenges that teachers encounter with including them as full participants in the class. This qualitative study draws on a purposive sample of 13 educators who have experience teaching children with ASD within two cities in Ontario, Canada. Through in-depth interviews we asked about teachers' challenges regarding creating an inclusive environment within their classroom. Teachers reported several challenges, including: understanding and managing behaviour; socio-structural barriers (i.e., school policy, lack of training and resources); and creating an inclusive environment (i.e., lack of understanding from other teachers, students and parents). Teachers recommend that more resources, training and support are needed to enhance the education and inclusion of children with ASD.