This study examines patterns of mother/child verbal interactions during task performance for differences related to the sex and locus of control (LOC) of the child. Subjects were 40 pairs of white, middle-class mothers and their children. The children--20 boys and 20 girls--were divided equally among first- and later-born 4- and 5-year olds. The children were classified as "Internals" or "Externals" on the basis of their scores on an appropriate LOC scale. The social interaction of each pair was videotaped during four tasks: two puzzle tasks and two sex-typed tasks. All verbalizations of each mother and each child were coded from the videotapes, and patterns in the flow of conversation between mother and child were examined. A mixed analysis of variance was used to examine effects of the child's sex, LOC, age or birth order on these probabilities. Boys and mothers of boys talked more than girls and mothers of girls. There were no significant differences in verbalization related to LOC, birth order, or age of the child. Sex differences in the overall amount and patterning of verbalization of boys vs. girls are discussed in relation to previous research in the area. (Author)