The purpose of this study was to investigate relationships among maternal childhood attachment, maternal attachment, and young children"s social and emotional behavior. The subjects of this study were 190 three-year-old children who attended child care centers located in Daegu city and their mothers. Data were collected utilizing the adult attachment scale, the mothers. affection measurement, and the child behavior scale. For data analysis, two-way ANOVA and Pearson.s product-moment correlation analysis were applied. The results of this study were as follows: First, positive emotion and expectation that are sub-factors of maternal attachment showed significant differences by gender. Positive emotion was higher for boys than girls, and expectation was higher for girls than boys. Self-sacrificing warmth and protection that are sub-factors of maternal attachment showed significant differences by employment type. Self-sacrificing warmth and protection were higher for full-time workers and housewives than part-time workers. Second, aggression, prosociality, being rejected, and overacting that are sub-factors of the children"s social and emotional behavior showed significant differences by gender. Aggression, prosociality, being rejected, and overacting were higher for boys than girls. Third, there was a negative correlation between maternal childhood attachment and the girl"s overacting. Forth, there was a negative correlation between maternal expectation and the young children"s overacting. The findings of this study are expected to provide basic data to support desirable attachment relationship between mother and child and actual facilitation of positive social-emotional behavior of children.