This study had two objectives: 1) evaluating the effects of an intervention program to develop social skills (communication, empathy, emotional regulation) in behavioral, cognitive and emotional variables; and 2) exploring whether the program affects differentially by gender. The sample comprised 148 adolescents, aged 13-16 years (83 experimental, 65 control). The study used a quasi-experimental repeated measures pretest-posttest design with a control group. Before and after the program four assessment instruments were administered: Social Attitudes and Cognitive Strategies (Moraleda et al. 1998/2004), Empathy Questionnaire (Merhabian & Epstein, 1972), Emotional Quotient Questionnaire (Bar-On & Parker, 2000), and Questionnaire of cognitive strategies of social interaction. The ANCOVAs pretest-posttest confirmed that the program significantly stimulated (p< .05) an increase in: 1) positive social behaviors (social conformity, help-collaboration, self-assurance-firmness), 2) empathy, 3) emotional intelligence (intrapersonal, interpersonal, general mood), and 4) cognitive strategies of social interaction assertive. The discussion focuses on the importance of implementing programs to promote social-emotional development during adolescence.