Social competence is considered one of the fundamental protection factors in the emergence of behavior problems since facilitates the social adjustment of subject and their psychological wellbeing. The investigation analyze the impact of a universal prevention program on three dimensions of social competence: cooperation, interaction and social independence. This is a quasi-experimental longitudinal study where the evolution of 91 children from 3 to 5 years of age is observed. Data analysis is carried out through a repeated-measures mixed ANOVA, where three factors were included: time (6 measurements), group and gender. Results show participant improvement on all the variables that were analyzed. The change becomes clearly evident in the experimental group after the first year of intervention, and this change continues over the next two years. There are small effects from the intervention program on social interaction (d = 0.20), moderate effects on social cooperation and social independence (d = 0.64 and d = 0.71, respectively) and large effects on the global measurement of social competence (d = 1.04).