BACKGROUND: The combined experience of autism and bilingualism is poorly understood, leading to poor support for autistic people in multilingual environments or those interested in languages. While most available studies focus on the language and cognitive profiles of autistic bilinguals, or on the experiences of parents, little is known about the lived experiences of autistic multilinguals. METHODS: To address this question, this study examined the impact of autism and multilingualism on the lives of 54 autistic multilingual adults who completed an online survey assessing the profiles of autistic bi- and multilinguals. We conducted a thematic analysis of responses to the survey's open-ended questions to explore motivations for learning languages and the perceived benefits of being both autistic and multilingual. RESULTS: There was a wide range of language profiles in the sample, with various levels of proficiency, ages of acquisition, and learning environments. Respondents felt that being autistic can both positively and negatively influence language learning. They reported various motivating factors for the acquisition of multiple languages, including social aspects and a predisposition for language learning. Respondents reported many benefits of multilingualism, such as educational, employment, or leisure opportunities; social skills and understanding of other people; self-confidence in their own abilities; and relationships with family, friends, and the worldwide autistic community. CONCLUSIONS: Unlike previous work with autistic multilinguals involving case studies, the larger sample involved here offers valuable insight into the profiles and experiences of this overlooked population. Importantly, autistic people can experience numerous benefits from multilingualism. These findings will have implications for language education practices as well as for multilingual families and the practitioners who support them. LAY SUMMARY: WHY WAS THIS STUDY DONE? We wanted to understand what it feels like to be both autistic and multilingual, in a world where it is often assumed that both cannot go together. The combined experience of autism and bilingualism is poorly understood. This leads to poor support for autistic people in bilingual environments or for those interested in languages. Most studies available focus on the language and mental abilities of autistic bilinguals, or on the experiences of parents. However, very few studies focus on the lived experiences of autistic multilinguals themselves. WHAT WAS THE PURPOSE OF THIS STUDY? The purpose of this study was to understand the experiences of autistic multilingual adults. We focused on their learning motivations and the perceived benefits of being autistic and multilingual. WHAT DID THE RESEARCHERS DO? Fifty-four autistic multilingual adults completed an online questionnaire designed for autistic bi- and multilinguals. The questionnaire included questions about the respondents' language history and language profiles. There were also open-ended questions about the respondents' motivations for learning languages, and their general experience of being both autistic and multilingual. We analyzed and summarized the responses to these open-ended questions to understand the experience of autistic multilingual adults. WHAT WERE THE RESULTS OF THE STUDY? Our sample had a diverse range of language profiles and experiences. Respondents thought that autism could be both an advantage and a disadvantage for language learning. They reported a range of motivations for language learning, including a predisposition for language learning. They considered relationships as both a motivation to learn languages and a benefit of multilingualism. Respondents thought that being multilingual had brought them many opportunities for leisure, travels, education, and employment. They considered that being multilingual had improved their self-confidence. They also thought that being multilingual had increased their awareness and understanding of autism, allowing them to connect with the wider autistic population. WHAT DO THESE FINDINGS ADD TO WHAT WAS ALREADY KNOWN? Previous research with autistic multilinguals involved only one or two participants. The larger group of autistic multilinguals involved in this study offers valuable insight into the lived experiences of this overlooked population. WHAT ARE POTENTIAL WEAKNESSES IN THE STUDY? The online questionnaire was not originally designed to collect in-depth data on lived experiences. This means that the questions included very few prompts: respondents were able to discuss the aspects of their experience that were the most important to them. The absence of specific topics in the results does not mean that they are not experienced, but simply that the participants did not spontaneously mention them. Future research should build upon our findings and focus on specific topics, such as learning environments or opportunities. HOW WILL THESE FINDINGS HELP AUTISTIC ADULTS NOW OR IN THE FUTURE? These findings will help autistic adults by highlighting the diversity and richness of their language profiles, abilities, and experiences. This will prompt families, educators, and practitioners to better support and include autistic people in multilingual environments or those interested in languages.