Thirty six preschool children, equally divided by sex, are used as subjects for this study. They are matched in parental educational level, socioeconomic level, chronological age, mental age, and intelligence quotient. Their language responses are observed under two different situations: (a) the child-child situation in which the subject is playing toys with another child, and (b) the adult-child situation in which the subject is discussing the content of pictures with the Experimenter. Fifty consecutive verbal responses are recorded in each situation for every child. Data thus obtained are subjected to analysis to determine: (1) the total number of words; (2) the mean length of sentence, (3) the total number. of different words, (4) the type-token ratio, (5) the percentage of the different4parts of speech, (6) kinds of sentences, and (7) the complexity of sentences. By employing techniques of i-test, F-statistic, and nonparametrics, it is found: (a) that there are no significant sex differences, except that girls seems to have a greater tendency than boys in using complex sentences, and (b) that there are significant differences between the language spoken in child-child situation and -that in adult-child situation.