Background: Utility-value interventions have been shown to promote students' achievement and motivation in mathematics through encouraging them to identify connections between course content and their real lives. To extend the benefits of these interventions, additional research is necessary to test their efficacy in diverse high school contexts, as well as investigate the psychological mechanisms through which they benefit students. Aims: To inform efforts within broader learning contexts to develop activities and messages based on utility-value interventions that effectively target the psychological mechanisms that support student learning. Samples: Study 1 (N = 375) and Study 2 (N = 2894) include racially and socioeconomically diverse samples of students enrolled in mathematics courses across four high schools in the United States. Methods: We conducted two randomized field experiments to test the effects of brief utility-value activities on students' motivation. Using multi-level path analyses, we then investigated the mechanisms through which utility-value activities bolster students' interest and achievement in mathematics. Results: In pre-registered analyses, we found that the utility-value activities promoted students' perceived value of mathematics, as well as their novel engagement and sense of social identity congruence with mathematics. In turn, these outcomes mediated the indirect effects of the activities on students' grades and interest in mathematics. Conclusions: Our results underscore the potential of utility-value activities to promote students' success. Based on our mediation findings, we also provide a roadmap for how learning contexts can develop activities and messages that effectively target key processes to advance student success.