Subscribing to global frameworks on inclusive education, such as the United Nations Convention on the Rights of Persons with Disabilities and Sustainable Development Goal 4, Nigeria has adopted inclusion as a major tenet for education policy. However, for autistic students, mainstreaming is associated with a unique paradox of “exclusion in inclusion” – a condition in which physical placement in a mainstream classroom does not translate into equitable participation or learning. Global literature supports that autistic students face multi-faceted challenges associated with attitudinal and structural barriers to learning in inclusive classrooms. In the Nigerian context, such barriers are compounded by limited awareness, cultural misconceptions, and uneven policy implementation. This study sought to identify, categorize, and analyse Nigerian teachers’ perspectives regarding teacher-related and systemic barriers faced by autistic students in mainstream classrooms. Employing a mixed-methods design, quantitative data were collected through a structured survey questionnaire that measures teachers’ attitudes, self-efficacy, and perception of adequacy of systemic resources, while qualitative data were collected using a semi-structured interview schedule, exploring lived realities of inclusion. Guided by the theory of planned behaviour, an explanatory framework to examine how attitudes, subjective norms, and perceived behavioural control influence intentions and actions of teachers towards autistic students in mainstream classrooms was presented. It was realised that prejudicial attitudes such as assuming that all autistic students are alike and incapable of developing skills, or overly demanding of systemic resources, low self-efficacy in teaching inclusively for autistic students, and reduced willingness to implement inclusive practices were major teachers’ implicit constraints. Furthermore, inadequate training, large class-sizes, insufficient teaching aids, and lack of community engagement were the key systemic barriers. The study outcome raises critical concerns regarding teacher training/sensitization, policy implementation, resource allocation, and community engagement strategies to move inclusion beyond physical placement towards meaningful participation. The study findings contribute to the global discourse on inclusive education in low-and medium-income countries, with implications for contextually responsive interventions, sustainable resource management, and a stronger and more nuanced policy implementation framework.

Keywords: Autism, inclusive education, Nigeria, social in(ex)clusion in classrooms, mainstreaming, teachers’ perspectives, Theory of planned behaviour, educational barriers.