BackgroundThe transition from childhood to adolescence is a uniquely sensitive period for social and emotional learning in the trajectory of human development. This transition is characterized by rapid physical growth, sexual maturation, cognitive and behavioral changes and dynamic changes in social relationships. This pivotal transition provides a window of opportunity for social emotional learning that can shape early adolescent identity formation and gender norms, beliefs and behaviors. The objective of this study is to evaluate the potential of a social emotional learning intervention for very young adolescents (VYAs) to improve social emotional mindsets and skills.MethodsDiscover Learning is a social emotional learning intervention designed for VYAs (10-11 years of age) to support development of social emotional mindsets and skills from four primary schools in Dar es Salaam, Tanzania. The intervention delivered three different packages of learning experiences to three arms of the study. 528 VYAs were randomized to each of the three study arms (A-Content learning, B-Content learning and reflection, and C-Content learning, reflection and experiential practice). A quantitative survey was administered to all participants before and after the intervention to capture changes in social emotional mindsets and skills. A discrete choice experiment measured changes in gender norms, beliefs and behaviors.Results528 VYAs were included in the analysis. Participants in all three arms of the study demonstrated significant improvements in social emotional mindsets and skills outcomes (generosity, curiosity, growth mindset, persistence, purpose and teamwork). However, Group C (who received experiential social learning opportunities in small, mixed-gender groups and a parent and community learning components demonstrated larger treatment effects on key outcomes in comparison to Groups A and B. Results indicate Group C participants had greater change in gender equity outcomes (OR = 1.69, p = <0.001) compared to Group A (OR = 1.30, p = <0.001) and Group B (OR = 1.23, p = 0.004).ConclusionThese findings provide evidence that social emotional learning interventions targeting VYAs can improve social emotional mindsets and skills and gender equity outcomes. The findings indicate the importance of experiential learning activities in mixed-gender groups during the unique developmental window of early adolescence. The study also provides support for the inclusion of parental/caregiver and community engagement in programs designed for VYAs.Trial registrationRetrospectively registered on July 7th, 2020. NCT0445807