Autism research and services have historically focused on individuals with a formal autism diagnosis. However, activists and self-advocates in the United States recognize that there are financial and clinical barriers impeding access to formal diagnostic evaluations for autism. Research also suggests that groups on the margins of autism, specifically those who are not White, young, or assigned male at birth, receive later diagnoses, if diagnosed at all. In particular, individuals who are autistic and LGTBQ+ are likely to not be afforded opportunities to be assessed and diagnosed. We conducted interviews with 65 queer and transgender autistic adults who either self-identified as autistic or had a formal autism diagnosis about their experiences with and perceptions of autism diagnosis. We found that participants derived a sense of meaning and affirmation from their autistic diagnosis and/or identity, faced significant barriers and deterrents to diagnosis, and experienced invalidation as both a barrier to and product of diagnosis. We argue that self-identified autistic individuals provide valuable context and data for many of the social processes and preferences reported by autistic people. We offer recommendations for research and services, specifically that many should not require formal autism diagnoses of participants. Lay abstract Most autism research and services focus on individuals with formal autism diagnoses. However, autism activists and self-advocates have raised awareness about the challenges that can prevent individuals from seeking or getting an autism diagnosis. We interviewed 65 queer and transgender adults who either self-identified as autistic without a formal diagnosis or who had a formal autism diagnosis. We found that participants made meaning of their autistic diagnosis and/or identity and found affirmation in this, faced significant barriers and deterrents to getting diagnosed, and experienced invalidation as both a barrier to and product of diagnosis. Due to the challenges that individuals face in getting a diagnosis, we recommend that researchers and advocates consider including self-identified autistic individuals in research and services.