In this study, we investigate the effect of time allocation on children's non-cognitive development, using data from the Millennium Cohort Study (UK) and focusing on children aged 7 and 11 years. We classify the time spent outside of school into seven groups of activities and evaluate their impact on five socio-emotional skills drawn from the Strength and Difficulties Questionnaire, leveraging the data's panel structure. We subsequently test the robustness of our estimates against endogeneity issues. Time spent on sports, studying, reading, tidying up and active time with parents have beneficial effects, while video-screen time and extra hours at school have harmful effects.