This essay outlines general criteria for evaluating the effectiveness of an existing or proposed sign system for libraries with respect to the needs of physically disabled library users, specifically the deaf, the blind, and those confined to wheelchairs. The function of the International Symbol of Access is described, and design considerations relating to the clarity and conspicuity of sign systems are summarized. Relevant standards for the evaluation of library sign systems are mentioned. An instrument for the evaluation of library sign systems for the disabled, reproduced from a publication of the State University of New York Construction Fund, is included with the text, as are illustrations of the International Symbol of Access, the Helvetica semi-bold typeface (especially legible, and thus appropriate for use on signs), signs for room identification, and signs indicating the location of elevators capable of accommodating wheelchairs. (Author/JL)