Anorexia nervosa (AN) and autism share a number of common features, including restrictive eating, cognitive rigidity, and social difficulties. However, these similarities make distinguishing between co-occurring autism and AN, and AN only, complicated. Diagnostic tools designed to identify autism in this population may not differentiate between features driven by “true” underlying autism, and pseudo-autistic features related to the AN illness state only. The ability to accurately identify autism cases in AN populations is clinically important, as autistic people with AN are at risk of poorer illness and treatment outcomes in the absence of appropriately adapted eating disorder treatments. To address this difficulty, the following paper presents a framework of clinical features associated with autism that are also common in AN, and outlines potential differences in presentation. Implications for the diagnosis and treatment of co-occurring autism and AN are then discussed. It is hoped that this framework will act as a useful tool for clinicians working with these populations, and encourage further research and discussion in this field.