A model of assessing language proficiency in hearing bilingual students is adapted and discussed in terms of hearing impairment needs. Empirical data are presented to verify that the language or system acting as a "first language" for hearing-impaired students in cognitive/academic stituations can be determined. Educational implications are discussed, including that hearing impaired students should be given the opportunity to demonstrate which of the potential languages are beneficial to them in learning academically-related skills. Four variables should be evaluated: (1) language and/or system of the caretaker; (2) onset date of exposure to sign language and/or systems; (3) degree of usable aided hearing ability; and (4) language and/or system demonstrated most effective for learning cognitively demanding/context-reduced tasks. (Author/CL)