Despite growing appreciation of the need for research on autism in adulthood, few survey instruments have been validated for use with autistic adults. We conducted an institutional ethnography of two related partnerships that used participatory approaches to conduct research in collaboration with autistic people and people with intellectual disability. In this article, we focus on lessons learned from adapting survey instruments for use in six separate studies. Community partners identified several common problems that made original instruments inaccessible. Examples included: (1) the use of difficult vocabulary, confusing terms, or figures of speech; (2) complex sentence structure, confusing grammar, or incomplete phrases; (3) imprecise response options; (4) variation in item response based on different contexts; (5) anxiety related to not being able to answer with full accuracy; (6) lack of items to fully capture the autism-specific aspects of a construct; and (7) ableist language or concepts. Common adaptations included: (1) adding prefaces to increase precision or explain context; (2) modifying items to simplify sentence structure; (3) substituting difficult vocabulary words, confusing terms, or figures of speech with more straightforward terms; (4) adding hotlinks that define problematic terms or offer examples or clarifications; (5) adding graphics to increase clarity of response options; and (6) adding new items related to autism-specific aspects of the construct. We caution against using instruments developed for other populations unless instruments are carefully tested with autistic adults, and we describe one possible approach to ensure that instruments are accessible to a wide range of autistic participants.