Research in high-income countries has established a relation between social and emotional learning (SEL) and academic achievement. However, evidence is lacking from low- and middle-income countries. In this paper we present two studies to address this lack of evidence. In the first study we analyse data from a nationally representative survey of SEL and literacy skills in Grades 1-3 in Kenya. In a multiple regression analysis, 4 of the 5 SEL skills measured – assessor-rated confidence, self-rated confidence, interpersonal negotiation strategies and peer relationships – were independently associated with literacy skills. In addition, children who perceived their learning environment to be supportive also had better literacy skills. A supportive learning environment was a stronger predictor of literacy skills for boys compared to girls. There were inequalities in academic achievement, with children in urban areas, and those with wealthy parents, having better literacy scores than poor children in rural areas. Up to 50% of the academic advantage of wealthy, urban children was explained statistically by their more advanced SEL skills and more supportive learning environment. The second study analysed data from the older cohort of children in the Young Lives longitudinal study. The data analyzed were collected from children in four rounds, when they were 12, 15, 19 and 22 years of age. We found a bidirectional relationship between agency (a child’s sense of control over their life) and their achievement in mathematics. In all countries, mathematics achievement was a predictor of subsequent levels of agency. We found that a child’s agency in a given round was associated equally with their agency and their mathematics achievement in previous rounds. In two countries – India and Vietnam – we also found a relationship in the opposite direction: mathematics achievement depended on previous levels of agency. These relationships are important because other analyses of the same data show that gender inequalities in self-efficacy and agency emerge in late adolescence, with girls increasingly lagging behind boys. An implication of both studies is that programs to promote SEL and supportive learning environments may help reduce learning inequalities based on wealth and between urban and rural students (Study 1) and inequalities based on gender (both studies).