Background Research suggests that families' knowledge and cultural perceptions of autism spectrum disorder (ASD), and beliefs about its etiology and prognosis, can affect parents' recognition of the first signs of autism in their children and influence help seeking and treatment decisions. Objective This study investigated explanatory models of autism among parents of young children with ASD in the multicultural context of Sweden. Method Seventeen parents from diverse cultural, ethnic and linguistic backgrounds participated in semi-structured interviews. A deductive approach to qualitative content analysis was used to analyze data. Five domains of the Explanatory Model supplementary module of the Cultural Formulation Interview (CFI) were used as coding categories, operationalized as 'Parents' understanding of autism'; 'Autism prototypes'; 'Causal explanations'; 'Course of autism', and 'Help seeking and treatment expectations' Results The results showed that parents' prior knowledge of autism and experience of young children's typical developmental trajectories, as well as the opinions of children's grandparents and preschool teachers, affected symptom recognition and help seeking. There were differences in parents' explanatory models before and after ASD diagnosis. Initial interpretations of the disorder included medical conditions and reaction to environmental influences, while genetic, supernatural/religious factors, and vaccinations were mentioned as definite causes after obtaining a clinical diagnosis. Parents also held multiple explanatory models,