This study examined if any differences exist of young children's physical and relational aggression as affected by aggression levels, teacher-child and peer relationship, age, and gender. Furthermore, the extent of physical or relational aggression of the young children influencing teacher-child relationships is also examined. In this study, two hundred and fifty children aged three to ten and fifty-two teachers were targeted. They responded on questionnaires in regard to aggression, teacher-child relationships, and peer relationship. The findings are as follows: First, in terms of child aggression according to his/her age, it has been shown that physical aggression is primarily present in the age of four. Second, concerning gender, boys are found to be high in levels of both relational and physical aggression. Third, the data shows that in the relationship between the child's aggression and teacher-child relationship, the higher the child’s aggression, the lower the intimacy of relationship between child and teacher and the higher the dependence and conflict in the relationship of teacher and child. Fourth, in the examination of relationships between a child's aggression and peer influence, higher levels of relational and physical aggression correlate with higher aggressive, hyperactive, and anti-social behaviors. In addition, the higher the age and relational aggression, the higher the pro-social behaviors that occur. Pedagogical implications and suggestions are put forth in the areas of improving relationships between children and teachers, how teachers can assist young learner development, and techniques to improve peer relationships and reduce its difficulties.