The investigators' overall objective is to demonstrate the efficacy of the Bullying Classroom Check-Up (BCCU) on elementary aged students' aggressive and bullying behaviors, teacher practices, and student and teacher relationships. The investigators' principal hypothesis is that the BCCU will improve students' aggression and bullying behaviors and their perceptions of the school climate and relationships in the building as well as teacher practices.

Aim 1: Examine the Efficacy of the Bullying Classroom Check-Up (BCCU) at improving child aggressive and bullying behaviors For this aim, the study team will examine student self-report measures and classroom observational data at post-test (end of year 1) and in the follow-up assessment (winter of following school year). The study team will focus on their own aggression and bullying behavior as well as their perceptions of the general bullying climate, rating of safety, and positive bystander behaviors (i.e., how students respond to bullying when they witness it). The study team hypothesize that children in schools randomized to the BCCU condition will be less likely to engage in aggression and bullying, will rate the general bullying climate (i.e., perceptions that bullying is a problem and that adults/students do enough to stop bullying) and sense of safety more positively, and engage in more positive bystander behaviors than children in schools randomized to the control condition.

Aim 2: Examine the efficacy of the BCCU at improving teacher practices and relationships For this aim, the study team will examine teacher and aggregated student self-report measures and classroom observational data at post-test (end of year 1) and in the follow-up assessment (winter of following school year). The study team will focus on teacher self-reported, observed, and student-reported classroom practices as well as perceptions from teachers and students about relationships within the school. The investigators' hypotheses are that teachers in the BCCU condition will engage in more preventive classroom management and intervention strategies (e.g., modeling social emotional competencies such as empathy) in response to bullying than teachers in the control condition, and that teacher-student and student-student relationships will be more positive in classrooms in the BCCU condition than in the control condition.

Exploratory Aim 3: Explore the moderating role of fidelity in the main outcomes of interest. Explore the mediating role of teacher self-efficacy and behavior management practices on distal outcomes.

For this exploratory aim, the study team will examine how fidelity indicators (e.g., dosage, coach adherence, as reported by coaches) moderates intermediate teacher outcomes (e.g., teacher practices) within the main effect models. The study team will also examine how changes in teacher intermediate outcomes (e.g., teacher efficacy and practices) relate to the follow-up year's classroom climate (e.g., relationships) as reported by students (aggregated) and teachers in mediation models.

Inclusion Criteria:

Inclusion Criteria - Schools 32 schools will be selected based on the following inclusion criteria:

1. Urban to urban fringe districts in the Northeast US
2. Predominately minority student body (> 65%)
3. Relatively large school with at least two 3rd, 4th, and 5th grade classrooms

Inclusion Criteria - Teachers 1) Teachers of 3rd-5th grade regular education classrooms employed by the participating school sites who provide their consent for participation.

Inclusion Criteria - Students

1) All students of consented teachers will be eligible to participate in survey activities.

Exclusion Criteria:

Exclusion Criteria - Teachers

1. Teachers in grades other than 3, 4, or 5 during the first year
2. Special education teachers
3. Specials (e.g., art, music) teachers

Exclusion Criteria - Students

1. Students who do not speak English.
2. Special education students who are not integrated within the regular education classroom (i.e., receive education in self-contained classrooms).