Recent studies have indicated that males make more egotistical attributions than females, that is, males make more internal attributions for success and more external attributions for failure than females do. These sex differences in attributions were examined in terms of male/female differences in expectancies for success and ego-involvement in the tasks. Male and female subjects succeeded or failed on a masculine or a feminine task. It was found that males made more egotistical attributions than females on the masculine task, but females made more egotistical attributions than males on the feminine task. A covariance analysis revealed that these sex differences in attributions could be explained in terms of the differences between the males and females in expectancy for success and in ego-involvement. Finally, it was found that ego-involvement was a more important determinant of egotisical attributions in the present study than was expectancy.