The comprehension ability of 36 children at three stages of telegraphic speech (mean length of utterance 1·45, 2·03, and 2·76 morphemes) was assessed using active behavioural responses to declarative and imperative sentences. Both forms were varied in syntactic and semantic complexity. The responses were scored in terms of objects used by the child, whether or not the child's actions were appropriate, and whether or not appropriate verbalization accompanied the actions. A significant increase in verbal and behavioural appropriateness with age was found for both imperative and declarative forms. Consistent with Shipley, Smith & Gleitman's (1969) results, advanced telegraphic speakers responded most often to adult stimulus forms. However, contrary to Shipley et al.'s findings, all children, even the earliest telegraphic speakers, were more accurate in responding to adult forms than to child forms, suggesting that ability to comprehend adult linguistic forms is present even at the earliest stages of telegraphic speech. The findings imply that re-evaluation of the development of comprehension ability in telegraphic speakers is necessary.