Background: The past few decades have seen a significant growth of research on socio-emotional skills development programs and on mental health education in schools since their key-importance has been well documented. This study presents the evaluation of “Steps for life”, an open, question-based, annual, teacher-taught, mental health Greek K-curriculum, designed to improve personal and social skills in young students aged 4 - 6. The curriculum uses classroom-appropriate methods such as dialoguing, story-telling, role-playing and diffusion in formal and hidden curriculum, while incorporating a considerable degree of parental involvement. Methods: The study was conducted in Greece during 2009-2010. The sample consisted of 998 kindergartners, with 518 of them forming the experimental group and 480 the control group. The questionnaire designed for the study consisted of items regarding demographics, of the Behavioural Academic Self-Esteem scale and of 8 more subscales, namely concentration of attention, participation and cooperation in the class, emotions’ identification and management, physical and verbal aggressiveness control, victimization control, self-esteem, empathy, friendship skills, and problem solving. Its 96-in total-items examined students’ behaviors as exhibited in the school environment and as observed and rated by their teachers. It was administered pre and post intervention to both groups’ educators. Results: The results suggest that both groups exhibited significant improvement in all investigated skills. As indicated by the regression analysis however, the intervention students showed significantly higher improvement in all targeted abilities except friendship skills. Conclusions: Our intervention improved more significantly almost all the taught skills, corroborating the findings of other researchers who found that similar approaches can improve children’s social and emotional skills. Therefore, it is important for schools and communities to identify and effectively implement evidence-based interventions.