Children living in rural areas are diagnosed with Autism Spectrum Disorder later than their non-rural counterparts. In rural areas, caregivers have limited access to ASD information and services. Caregivers play a central role in early diagnosis and intervention, only when they have current knowledge about early ASD symptoms. The purpose of this paper was to understand caregivers' knowledge of ASD behaviours and its aetiology and to explore if there were differences between rural and urban caregivers' knowledge about ASD. One hundred and eighty-five Alabama caregivers answered two open-ended questions on the causes and behaviours of ASD as part of a larger survey. This report focuses on a qualitative textual analysis of the open-ended questions. Eight themes emerged regarding ASD behaviours including communication, emotion and behaviour, heterogeneity, unknown, learning and development, other, repetitive and sensory behaviours, and social impairments. Ten themes emerged regarding aetiology including born with it, cause unknown, combination, environmental, genetic/environmental interaction, genetics/chromosomal I do not know, neurological, other, and pregnancy. Both rural and urban caregiver groups reported behaviours associated with diagnostic criteria. However, urban caregivers reported behaviours more proximal to DSM-5 diagnostic criteria while rural caregivers reported behaviours less specific to ASD. Findings may help better understand why children in rural communities receive later diagnoses.