This research focused on the initial stage of language development of a hearing child who was acquiring simultaneously both spoken English and American Sign Language (ASL). The report covers the first phase of the longitudinal research on the child's linguistic development, focusing on early word meanings. The data were collected from the time when the first sign emerged at 7 months, 6 days, to the age of 21 months. The child was videotaped at home during 30-minute play sessions at which both parents were present. The most important findings concern the relationship between the child's conceptual and linguistic systems. Three stages in semantic acquisition were traced in both ASL and English. It was demonstrated that expressing concepts and referring to "reality" can be accomplished with manual signifiers as easily as, or more readily than, with spoken words. It was concluded that, although the rate of lexical acquisition during early stages of language development might be delayed as a result of bilingual learning, more direct exposure to a visual language, such as ASL, might enhance communicative effectiveness at an early stage of a child's development. (AMH)