People on the autism spectrum can learn about autism from various sources, likely differing in the information, portrayal, and discussion they offer. The present study investigates where autistic people learn about autism, and whether their information source is associated with their level of autism knowledge, perceptions of stigma, and development and expression of an autism identity. A survey of 198 Australian adults with an autism diagnosis showed that learning about autism from conventional sources (e.g., professionals, parents) was associated with more internalised stigma, lower endorsement of special abilities and autism identity, whereas online blogs and social media showed the opposite pattern as well as more accurate knowledge of autism. The findings raise questions about how authoritative sources of information discuss autism.