Autism presents in a multitude of different and highly nuanced ways – particularly as it intersects with variance in class, gender, race and age. Misunderstanding and misinformation around variant and differing presentations means that misdiagnosed individuals and those who do not receive a diagnosis at all are often failed by medical, education, social care and criminal justice systems. They are detained in inappropriate settings; don’t receive beneficial therapeutic input; have their families accused of fabricated or induced illness (FII); are kept in prison or youth offending institutions longer than their original tariffs, and shockingly their life expectancy is often curtailed as a result. This comprehensive resource will help multidisciplinary professions to understand, contextualise, and better identify diverse autistic presentations. It includes an overview of the autism diagnostic process, an exploration of controversial and commonly confused diagnoses such as PDA, ODD, CD, ASPD, and BPD; discussions of best practice for investigating FII; and analysis of the specific challenges of autism diagnosis in relation to women and girls, BAME communities, schools, and the criminal justice system.