Researchers have been studying school aggression (often termed bullying) for many years, but it was not until the 1980's that the deleterious effects of school aggression became more apparent. Most of the studies on physical and relational aggression focus upon the experiences of children who perpetrate these actions or who are the victims of this form of aggression. However, few studies have investigated how physical and relational aggression is influenced by the teacher and/or specific classroom environments. To date, there is a scarcity of information available regarding teacher characteristics and attitudes within the classroom and how these specific characteristics are associated with physically and relationally aggressive behavior and the overall climate of the classroom. The purpose of the present study was to examine whether teacher positivity is associated with student levels of physically and relationally aggressive behaviors in the classroom. This study specifically examined the relationship between (1) teacher positivity and student physical and relational aggression, (2) the relationship between classroom climate variables and student physical and relational aggression, and (3) differences in school, teacher, student, and classroom variables (teacher and student gender, student grade, and student ethnicity) based on the level of teacher positivity. Data were collected from 502 male (n=259) and female (n=243) 3rd, 4th, and 5th grade students from two large urban elementary schools within the School District of Philadelphia during the 2005-2006 and 2006-2007 school year. In addition to student participants, the third, fourth, and fifth grade teachers (n=18) also participated as part of the focus of a systematic observation tool developed by the lead researcher. Results from the first research question found no significant correlations between teacher positivity and non-compliant acts, the proportion of physically aggressive students or the proportion of relationally aggressive students. However, the proportion of physically aggressive students was significantly positively correlated with the average number of non-compliant acts (r = .603, p = .008). Results from the second research question found that the average number of non-compliant acts and the proportion of physically aggressive students was higher in classrooms where the minority of students was engaged and interested in the classroom activity. Results from the third research question showed only that there were differences between School 1 (m = 0.49, sd = .09) and School 2 (m = .29, sd = .14; t (16) = 3.56, p = .003) when comparing teacher positivity by school. Teacher, student, and classroom variables did not produce significant findings. Post hoc analyses, looking more specifically at the types of redirection and praise which composed the teacher positivity score, found correlations between the average number of noncompliant acts and universal redirections (r = .795, p = .000), the proportion of physically aggressive students and total teacher redirection (r = .479, p = .036), the proportion of physically aggressive students and specific teacher redirections (r = .540, p = .021), and the proportion of relationally aggressive students and teacher redirections (r = .477, p = .045) that occurred during an interruption. / School Psychology