The study of sign language reveals the effect of the modality of communication on the language system. This paper presents a comprehensive description and discussion of the manifestation of time, space, and person reference in American Sign Language. It is in this area that the effect of the modality on information transmission appears most clearly. Various aspects of space, time, and person are discussed: the manner in which visual language allows for deictic and anaphoric locative, temporal, and 'pronominal' reference, the surface manifestation of the conceptualization of time, the specialized use of the dominant and non-dominant articulators, the contrast between the 'segmental' nature of oral-language spatial terms and the continuous nature of locative expressions in ASL, and the manner in which verbs may incorporate agent and/or patient and manner adverbials.*