The purposes of this study were to find out about the associations between hostile attributional bias and aggressive behaviors among preschool-aged children and to identify possible sources of their hostile attributional bias. Seventy-two preschoolers with an average age of 4.76 and their mothers acted as participants. Children's hostile attributional bias was examined using videotaped vignettes developed for this study. Children's aggressive behaviors were assessed by teachers and parents separately. As possible sources of children's hostile attributional bias, mothers' attributional styles, parenting behavior, affect, and some demographic information were collected via questionnaires. The relationships between children's aggressive behavior, mothers' attributional styles, parenting behavior, and affect were also investigated. Consistent with previous studies on school-aged children, results indicated that aggressive preschoolers, as assessed by teachers, were more likely to have a hostile attributional bias than nonaggressive ones. On the other hand, children's aggressiveness, as assessed by their mothers, was significantly related to their mothers' parenting behaviors, but not to their hostile attributional bias. Mothers of aggressive preschoolers reported less positive parenting behaviors than those of less aggressive ones. Mothers' affect did not show such an effect. Although mothers' specific attributional styles did not have a direct effect on their parenting behavior and affect, their general attributional style had a moderating effect on their affect, suggesting a reciprocal relationship between mothers' affect and their children's aggressive behavior. Mothers' specific attributional style, parenting behavior, and affect were not identified as sources of children's hostile attributional bias, but family SES was. Children from lower SES families were more likely to have a hostile attributional bias than those from higher SES families. Findings were discussed relative to previous theory and research, and suggestions for future research and implications for preschool teachers were made. / Graduation date: 1996