This study explores the role that gesture plays in the earliest stages of language learning. We describe how one-word speakers use gesture in combination with speech in their spontaneous communications, and interpret gesture presented in combination with speech in an experimental situation. Forty one-word speakers (ages 1;2.22 to 2;4.6) were videotaped in a free-play session which provided data on the child's spontaneous gesture and speech production. The children were also given a comprehension task in which the presence and absence of gesture were systematically varied in relation to speech. We found that (1) all of the children spontaneously produced gestures in combination with speech, and (2) all of the children were able to understand gesture when it was presented in combination with speech, not only when the gesture was redundant with speech but also when the gesture substituted for speech. These data suggest that, even at this young age, gesture naturally forms an integrated system with speech in both production and comprehension.