Student learning and achievement in schools are boosted by having positive motivational sets that allow learners to regulate their learning processes and sustain their efforts through the challenges in the different learning areas more effectively. This study inquires into whether the benefits of positive motivational sets are stable or variant in educational systems that have socioeconomic inequality. Philippine data from the PISA 2022 survey were analysed to study this proposition. The Philippines is one of the countries where the socioeconomic gap in achievement has increased in recent years according to the PISA results; understanding the specific effects of socioeconomic inequality on student learning is an important concern. The relationship between positive motivation variables in mathematics (mathematics growth mindset, curiosity, mathematics self-efficacy, and mathematics perseverance) and mathematics performance of 15-year-old Filipino students (n = 7127) were analyzed. The moderating effect of socioeconomic status (ESCS) was assessed using the PROCESS module of JASP (v. 0.19.3). The results consistently show that students from lower SES groups benefit less from positive motivations. The moderating effect of SES on mathematics growth mindset and mathematics performance was small but significant (coefficient of moderation = .01, CI = .01, .02), but the moderating effect of SES on curiosity (coefficient of moderation = 1.64, CI = 1.03, 3.25) and mathematics perseverance (coefficient of moderation = .78, CI = .36, 1.20) were relatively larger. The moderating effect of SES on mathematic self-efficacy was not significant (coefficient of moderation = .44, CI = -.26, 1.15). In three of the motivational variables, poverty weakened the positive relationships between mathematics motivation and achievement. As teachers in school try to develop strong learning motivations among students, deprivations in the students' environment diminish the positive impact of these important psychological functions on student learning. Implications for performance-directed and SES-targeted interventions are discussed.