Functional analysis has been shown to effectively identify the function of challenging behavior and inform the design of function-based treatment that emphasizes reinforcement-based procedures. However, there is minimal research on culturally responsive approaches to functional analysis with bilingual clients with a developmental disability who speak English and Spanish. This study evaluated a method of individualizing assessment conditions using culturally relevant variables, analyzing the data to evaluate the influence of language on functional analysis outcomes and considering the influence of language proficiency and preference on functional analysis results. The data for the influence of language on functional analysis were analyzed separately, which highlighted areas for further exploration and consideration with caregivers that likely would have been missed if the functional analysis had been conducted solely in one language. The influence of language during behavioral assessment and considerations of these variables in clinical practice for bilingual communities are discussed.