Inclusion is now the preferred method of educating children with disabilities in New South Wales public schools. Inclusion gives all students the same rights as their peers to be educated in a mainstream classroom regardless of disability. While this government policy does give all students an equal opportunity, teachers are the ones who need to include these children and their attitude towards inclusion can determine whether inclusion will be successful or unsuccessful. This research project investigates the perceptions and attitudes of a group of mainstream teachers, in NSW public schools, towards the inclusion of children with intellectual disabilities. Teachers were asked to respond to a questionnaire and in a follow up interview to identify their perceptions of different aspects of inclusion. This research identifies that teachers' perceptions and attitudes towards inclusion were based on experience and their sense of self efficacy. The availability of support contributed to these perceptions, as teachers felt they needed a supportive environment in order to successfully include a child with an intellectual disability in the mainstream classroom. Inclusion gives students an equal opportunity, but the teacher of the child must be fully supportive of inclusion. Teachers need to have a high self efficacy and be in a supportive environment to successfully include a child with an intellectual disability.