Tools for Life®: Relationship-Building Solutions (TFL) is a program designed to improve school climate and safety through the proactive development of elementary and middle school students' interpersonal skills (relationship-building and communication) and intrapersonal skills (self-regulation and resiliency). In the 2016–2017 and 2017–2018 school years, the Jackson (Mississippi) Public School District (JPSD) implemented TFL in grades 1 through 8. RAND researchers conducted a randomized controlled trial to determine whether TFL, integrated into existing school practices, positively affected school climate and safety in the district. In this report, they describe the implementation of TFL in JPSD, calculate its costs, and evaluate the program's effectiveness.,TFL is designed to improve whole-school change in relationships among staff and students, but the authors found that implementation of TFL in JPSD schools was generally shallow, and the program was rarely, if at all, implemented across a whole school as it was designed. TFL had little impact: After one year of implementation, there were no practically or statistically significant differences between schools that implemented TFL and those that did not in measures of students' social and emotional, school climate, behavioral, or achievement outcomes. In addition to the uneven implementation of the program, the authors discuss how methodological limitations of the study and contextual factors in JPSD may have contributed to these findings.