This study proposes to (1) explore the responses of boys and girls at three age levels to several different barrier situations; (2) assess the personality correlates associated with barrier behavior; (3) evaluate covariance differences between the sexes; and (4) determine the relationship between barrier behaviors and sex-role typing. A total of five barrier tests were administered at ages 3.5, 4.5, and 5.5 years. A central measure, the barrier intensity score (BI), was obtained by an observer who rated the intensity of the child's efforts to overcome the barrier. A personality characterization of each child was obtained from sets of teacher ratings. Results show an absence of sex differences in means and sigmas of BI scores; however, reliable differences in the correlational patterns associated with BI as a function of sex suggest that instrumental behavior in response to barriers is moderated by different psychological structures in boys and girls at age 4. These findings imply that analysis of covariance is essential in the evaluation of sex differences in barrier research. (GO)