Research of internalized problems during school years shows their stability and tendency of enhancement during the period of growing up. There are many challenges children and adolescents have to face: greater academic expectations, changes in relationships with parents and peers, physical changes, and transitions. Given the context and their background, students’ feelings such as shy or withdrawn behavior, frequent worrying, sadness, loneliness, and low sense of self-worth are unavoidable part of every classroom. Childhood and adolescence seem to be a critical age for prevention of internalized problems, and schools seem as a natural setting to support the accumulation of positive experiences that outweigh risks. When thinking about general evidence-based approach to internalized problems, findings show that is crucial to educate youth how to develop active coping strategies and to cope with negative thoughts. Schools can be good environments to do that. The aim of this chapter is to offer an overview of critical epidemiological data on internalized disorders of children and youth as well as a summary of evidence-based practices focused on their prevention in schools, going from universal to targeted programs and highlighting mindfulness-based interventions. Finally, Croatian example of investments in socioemotional learning is presented, examining its effects on students’ internalizing symptoms.