Background: Students who do not acquire social and emotional skills are at risk for a range of negative outcomes that include emotional and behavioral disabilities, lower school achievement and school failure, peer rejection, substance abuse, and school dropout (Downer & Pianta, 2006; Riggs et al., 2006 Quinn & Poirier, 2004). Tools for Getting Along (TFGA) is a cognitive-behavioral intervention that aims to teach children to understand others' intentions, generate multiple solutions to social problems, and choose appropriate responses (Daunic et al., 2006; Smith & Daunic, 2006), thereby reducing anger and behavior problems while increasing executive functions and social problem-solving skills (Smith et al., 2009). Purpose: In this study, researchers examined the effectiveness of TFGA, a classroom-based social problem-solving intervention, on the social-emotional and behavioral outcomes of grade 4 students. We addressed the following research questions: (1) What are the impacts of TFGA on students' social-emotional and behavioral outcomes? (2) Are there differential effects of TFGA for relevant subgroups of students (e.g., students who exhibited more behavioral difficulties at baseline)? We sought to understand the impact of the TFGA curriculum on student outcomes when fourth grade teachers in geographically and demographically diverse areas implemented the program in their classrooms with minimal training and under routine conditions. Setting: Students and teachers from 50 elementary schools in 11 school districts across three states (California, Oklahoma, and Kentucky) participated in this study. The districts varied in size and degree of urbanicity. Students from 10 of the 11 districts were majority white (73%-99%), and students from one district were 64% Asian, 18% Latinx, and 13% white. The percentage of families with incomes below the poverty level ranged from 6.9% to 33%. Participants: Across three cohorts, the study sample comprised 50 elementary schools (24 TFGA, 26 comparison), 135 grade 4 teachers (63 TFGA, 72 comparison) and 1,795 students (850 TFGA, 945 comparison) (See Figure 1). All grade 4 students participating in general education classes were eligible to participate in the study. Intervention: TFGA (Daunic et al., 2006; 2012; 2019) is a classroom-based intervention designed to help upper elementary teachers establish a positive, cooperative classroom atmosphere and enable students to become more effective and proactive problem solvers as they encounter social challenges. TFGA is theoretically aligned with Crick and Dodge's (1994) social information-processing model. Because anger is a frequent correlate of disruptive and aggressive behavior and is often preceded by frustration, the instructional focus of TFGA involves a sequence of problem-solving steps useful for understanding and dealing with frustration and anger. The intervention includes 21 core lessons delivered twice per week and 6 "booster" lessons delivered once per week. These lessons help students use the problem-solving steps to recognize and manage anger and to generate, implement, and evaluate solutions to emotionally charged situations. TFGA is designed to be teacher friendly, self-contained, and easy to implement in routine classroom practice. Lessons incorporate direct instruction, modeling, guided practice, independent practice, and skill generalization. In the current study, researchers trained to reliability observed a sample of 292 TFGA lessons, and we found that teachers typically delivered 88% of the key components of the lessons with most rated at average or higher quality (89%). Research Design: Using a cluster randomized controlled trial (RCT) design, we randomized schools (blocked by district, number of grade 4 classrooms, and school-level English Language Arts scores) to either the TFGA or comparison condition. Data Collection and Analysis: This study collected baseline and posttest data on students' social-emotional skills and behavior using the Behavior Rating Inventory of Executive Function Teacher Form (BRIEF) (Gioia et al., 2000) and Clinical Assessment of Behavior Teacher Rating Form (CAB-T) (Bracken & Keith, 2004). The BRIEF includes three indexes (behavior regulation, emotion regulation, and cognitive regulation) and a total score. Lower scores on the BRIEF indicate higher levels of functioning. The CAB-T includes 4 subscales: internalizing, externalizing, social skills, and competence. We obtained student gender, race, age, and language proficiency from school records and extracted school characteristics from publicly available data repositories. We conducted hierarchical linear model (HLM) analyses with students nested within schools to compare the TFGA with the comparison group from pre- to post-test. Schools were modeled as a random effect, and district and cohort were modeled as fixed effects. We included baseline measurements, student demographic characteristics, and school-level percent free or reduced-priced lunch as covariates to reduce residual variability. Results: Table 1 shows the demographic characteristics and outcomes of the study sample. There were no significant differences between treatment and control student demographics and baseline scores. Primary estimates of the intervention effect were derived from the intent-to-treat analyses. Table 2 demonstrates that the TFGA group had significantly higher levels of social skills ([beta] = 1.64, p = 0.0327, g = 0.12), behavioral regulation ([beta] = -1.06, p = 0.0076, g = -0.10), emotional regulation ([beta] = -0.87, p = 0.0165, g = -0.08), cognitive regulation ([beta] = -2.37, p = 0.0125, g = -0.12), and overall executive functioning as indicated by the total BRIEF score ([beta] = -4.38, p = 0.0069, g = -0.11) at post-test than the comparison group. Table 3 demonstrates that in addition to the main impact of TFGA, the interaction between student baseline scores and treatment were significant, suggesting that students with more social-emotional and behavioral difficulties at baseline experience greater reductions in internalizing behaviors and greater improvements in behavioral regulation, emotional regulation, cognitive regulation, and social skills. Conclusions: The findings from this effectiveness study indicate that the TFGA program has robust positive impacts across student demographics, geographic locales, and socio-economic levels. TFGA is effective in strengthening students' executive functioning and social skills, which are important components of social problem-solving. The program is particularly beneficial for students in need of greater social-emotional support. Furthermore, because the study was conducted under "real-world" conditions, teachers' ability to implement TFGA at a high level of completion and quality with minimal training indicates that TFGA is a feasible, low-burden option for educators to support upper elementary school students' foundational social-emotional skills.