Although the role of visual perception is central to many theories of language development, researchers have disagreed sharply on the effects of blindness on the acquisition process: some claim major differences between blind and sighted children; others find great similarities. With audio-and video-recorded longitudinal data from six children (with varying degrees of vision) aged 0; 9–3; 4, we show that there ARE basic differences in early language, which appear to reflect differences in cognitive development. We focus here on early lexical acquisition and on verbal role-play, demonstrating how previous analyses have failed to observe aspects of the blind child's language system because language was considered out of the context of use. While a comparison of early vocabularies does suggest surface similarities, we found that when sighted peers are actively forming hypotheses about word meanings, totally blind children are acquiring largely unanalysed ‘labels’. They are slow to extend words and rarely overextended any. Similarly, although verbal role-play appears early, attempts to incorporate this kind of language into conversations with others reveal clear problems with reversibility – specifically, the ability to understand the role of shifting perspectives in determining word meaning. Examination of language in context suggests that blind children have difficulties in just those areas of language acquisition where visual information can provide input about the world and be a stimulus for forming hypotheses about pertinent aspects of the linguistic system.