The educational goals of schools and all-day schools in Germany includes also support and strengthening of students‘ social-emotional competences. Extracurricular activities, extended education, can facilitate the students‘ development and strengthen their socio-emotional competences. Studies from the US reveal that programs are especially effective, e.g. for students‘ social behavior, if they are sequenced, active, focused, and explicit (SAFE) (Durlak, Weissberg & Pachen, 2010). These quality characteristics are implemented in the present program to assess the effects on socio-emotional competences of students. This intervention study with a pre-, post- and follow-up design examines whether a guided, universal and preventive interventional program fosters the socio-emotional competences of students in all-day primary schools in extended education and is accepted by the involved stakeholders. The sample, treatment and control group, comprises N=160 students (Grade 2 to Grade 4) at ten open all-day primary schools in the school year 2021/22 in Bavaria, Germany.