Significant research has been conducted on skills' enhancement school programs, since their importance has been well established. The presented study evaluates "Steps for life", a Greek, universal, annual, teacher-taught programme, designed to improve personal and social skills in young elementary students by the use of questions, diffusion in formal and hidden curriculum, and parental involvement. The experimental study was conducted in Greece during 2013-2014. The sample consisted of 2439 students, with 1516 forming the experimental group and 923 the control group. The study questionnaire included demographics, Personal and Social Skills Scale-Elementary, and the BASE scale. It investigated students' self-esteem, concentration of attention, participation/cooperation, emotions' identification and expression, emotions' management, ability to control verbal and physical aggressiveness, ability to control victimization, empathy, friendship skills, problem-solving, ability to take responsibility, and use of spoken and written language. The experimental group exhibited significant improvement in all investigated skills post-intervention, while the control group did not improve concentration of attention, emotions' management, and their ability to control verbal and physical aggressiveness and victimization. The analysis also revealed that intervention students had significantly higher improvement than the controls in all dimensions. Appropriately designed mental health promotion programs can improve several children's social-emotional skills and abilities.