Background – Eating difficulties in autism are common but under-researched, and perspectives and experiences of autistic people are under-represented. Existing sociocultural theories of eating difficulties, centring on negative body image, are based on neurotypical populations. They do not effectively explain eating difficulties that present differently in autistic people, potentially due to sensory and social differences and preference for sameness. To ensure autistic eating is effectively supported, there is a need to inductively conceptualise and measure eating behaviour in autism, including – but not limited to – symptoms of clinical eating disorders. Objective – Working in partnership Autistica and with autistic people, to co-produce this research, this project will conceptualise eating behaviour in autistic adults for the first time, and subsequently develop a measure of eating behaviour in autistic people. Methodology – Study 1 will investigate autistic experiences of eating behaviour via a qualitative, online focus group study (total N=45). This will provide new insights on autistic eating to inform the development of a concept map of autismspecific eating behaviours. Study 2, an online quantitative survey of 250 autistic adults, will compare sociocultural and autism-specific constructs of eating behaviour. Study 3 will use a Delphi process, involving lived experience experts and research experts, to develop consensus around an autismspecific measure of eating behaviour. Impact – My research will improve the conceptual understanding of the full range eating behaviour from the autistic perspective. This will guide potential adaptations to support autistic people with eating difficulties and also reduce inappropriate identification of non-pathological eating behaviours as disordered.