This article describes the case of a deaf native signer of American Sign Language (ASL) with a specific language impairment (SLI). School records documented normal cognitive development but atypical language development. Data include school records; interviews with the child, his mother, and school professionals; ASL and English evaluations; and a comprehensive neuropsychological and psychoeducational evaluation, and they span an approximate period of 7.5 years (11;10-19;6) including scores from school records (11;10-16;5) and a 3.5-year period (15;10-19;6) during which we collected linguistic and neuropsychological data. Results revealed that this student has average intelligence, intact visual perceptual skills, visuospatial skills, and motor skills but demonstrates challenges with some memory and sequential processing tasks. Scores from ASL testing signaled language impairment and marked difficulty with fingerspelling. The student also had significant deficits in English vocabulary, spelling, reading comprehension, reading fluency, and writing. Accepted SLI diagnostic criteria exclude deaf individuals from an SLI diagnosis, but the authors propose modified criteria in this work. The results of this study have practical implications for professionals including school psychologists, speech language pathologists, and ASL specialists. The results also support the theoretical argument that SLI can be evident regardless of the modality in which it is communicated.