This study explored the development of verbal behaviours of infants during two mother–infant games. Twenty-five infants were videotaped as they played peek-a-boo and ball with their mothers at 0;6, 0;9, 1;0, 1;3, 1;6, and 2;0. The frequencies of eight categories of vocal/verbal behaviours were analysed as they evolved over time in both games. Despite differences in the structure and level of difficulty of peek-a-boo and ball, the development of these behaviours proved to be similar in the two games. One category, PRIMITIVE VOCALIZATIONS, which did not change in frequency over time, was seen to have a pragmatic rather than a linguistic function. Another category, PRELEXICAL COMMENT, demonstrated an early capacity for conveying topic and comment together in the form of speech sounds combined with an attentiongetting gesture well before the emergence of multiple-word utterances. The vocal behaviours produced during games were compared with the results of language tests administered during the experimental sessions. Strong correlations were found between the results of these two measures of language. The predictive nature of vocal behaviours during games is discussed.