This study reports analyses, in terms of five different measures, of the speech on two standard tasks of thirty-two middle-class mothers to their children aged one and a half, two and a half, four, and six years. Sex and birth order of child were not found to be related to mother's speech. On four of the measures, both

task and age of child had strongly significant effects. In general, with increasing age of child, mothers spoke more, in longer and grammatically more complex utterances, with greater diversity of vocabulary. The differences in speech addressed to one-and-a-half-year-olds and that addressed to two-and-a-half-year-olds were particularly marked.