BACKGROUND: Autistic adults receive unfavorable first impressions from typically developing (TD) adults, but these impressions improve when TD adults are made aware of their diagnosis. It remains unclear, however, how autistic adults form first impressions of other autistic adults, and whether their impressions are similarly affected by diagnostic awareness. METHODS: In this study, 32 autistic and 32 TD adults viewed brief videos of 20 TD and 20 autistic adults presented either with or without their diagnostic status and rated them on character traits and their interest in interacting with them in the future. RESULTS: Findings indicated that autistic raters shared the TD tendency to evaluate autistic adults less favorably than TD adults, but these judgments did not reduce their social interest for interacting with autistic adults as they did for TD raters. Furthermore, informing raters of the diagnostic status of autistic adults did not improve first impressions for autistic raters as they did for TD raters, suggesting that autistic raters either already inferred their autism status when no diagnosis was provided or their impression formation is less affected by awareness of a person's diagnosis. CONCLUSIONS: Collectively, these results demonstrate that autistic observers make trait inferences about autistic adults comparable with those made by TD observers-suggesting a similar sensitivity to perceiving and interpreting social signifiers that differ between TD and autistic presentation styles-but unlike their TD counterparts, these trait judgments are not perceived as an impediment to subsequent social interaction and are relatively consistent regardless of diagnostic disclosure. LAY SUMMARY: Typically developing (TD) adults often form negative first impressions of autistic adults and report less of a desire to interact with them. These biases affect the social experiences of autistic adults and can contribute to their social disability. More optimistically, however, first impressions of autistic adults improve when TD adults are more knowledgeable about autism and are made aware of their diagnostic status, suggesting that familiarity and understanding can promote acceptance of autistic differences. One group that has high familiarity with autism is autistic adults themselves, but no study to date has examined how autistic adults form impressions of TD adults and other autistic adults. The purpose of this study was to examine whether first impressions of, and social interest in, autistic adults differ between autistic and TD raters, and determine whether disclosure of a person's diagnosis affects these patterns differently for autistic and TD raters. A total of 32 TD and 32 autistic adult raters viewed videos of 40 unfamiliar adults (20 TD and 20 autistic individuals) and rated each person on six traits (awkwardness, attractiveness, assertiveness, likeability, trustworthiness, and intelligence) and four items assessing their social interest in future interaction with the person in the video. Videos were presented either with or without the person's diagnosis to see whether this information affects impressions formed by autistic and TD raters. Consistent with prior work, TD raters formed more negative first impressions of autistic adults than TD adults. Meanwhile, autistic raters formed more positive impressions overall, but shared the TD pattern of rating autistic adults less favorably than TD adults on several traits. However, contrary to theories about reduced social motivation in autism, autistic raters expressed greater interest than TD raters in future interaction with people in the videos and this social interest was largest for other autistic people. Finally, diagnostic disclosure improved impressions of autistic adults made by TD raters but not by autistic raters. These findings provide empirical evidence that autistic adults detect and interpret autistic social differences similarly to TD adults, but they express greater inclusivity and less discriminatory attitudes about these differences. These results add to a growing literature about how autistic people are perceived, how these perceptions affect their social experiences, and how similarity between social partners can support social connection. The included sample was predominantly Caucasian and male, and did not include participants with intellectual disability. Future studies should examine whether the patterns here extend to more diverse samples. This study provides additional evidence that social opportunities for autistic adults are affected by the perceptions and biases of potential social partners. Autistic observers may share the TD bias toward less favorable trait evaluation of autistic adults, but this did not lessen their social interest in interacting with autistic adults the way it did for TD observers. Opportunities for autistic adults to interact with other autistic adults may facilitate relationship development in this population who often struggle to have their social needs met. In addition, findings suggest that acceptance of autistic people increases with familiarity of autism itself. Improving attitudes about autism among TD people may be one effective way to improve the social experiences of autistic people within neurotypical environments.