Types and amount of private speech (aloud talking which is not addressed to another person) were assessed during the free play of 16 hyperactive and 16 non-hyperactive boys (6-10 years old). Verbalizations were coded into nine categories which denoted the boys' level of use of verbal control of their own behavior. Differences in amount and type of private speech between hyperactive and non-hyperactive Ss were found which indicated that hyperactive boys may be presenting a specific or general cognitive lag in development. (Author)