Background: Social skills allow people to convey their wishes and emotions more effectively, improving their emotional intelligence and providing them with a greater sense of happiness and self-esteem. Aim of the study: This study aimed to investigate the effect of social skills' training program on emotional intelligence, happiness, and self-esteem among adolescent girls. Subjects and Methods; Research design: A descriptive cross-sectional design was adopted to carry out this study. A quasi-experimental design was used in carrying out this study. Setting: This study was conducted at El-Shaheed El-Sayed Fathy Gamaan governmental secondary school for girls in Abu Kabeir City, Al-Sharkia Governorate. Subjects: A purposeful sample of 73 adolescents in the pre-test as well as the same sample in the post-test was recruited. Tools of data collection: Five tools were used in this study: A socio-demographic data sheet, Matson Social Skills Questionnaire, Emotional Intelligence Scale, Oxford Happiness Questionnaire, and Rosenberg Self-Esteem Scale. Results: The majority of surveyed adolescents had low levels of social skills, emotional intelligence, and happiness at Pre-intervention. As well; more than two-thirds of them had low self-esteem levels. After the training program, there were highly statistically significant improvements in the mean score of social skills, emotional intelligence, happiness, and self-esteem. There was only a highly statistically significant positive correlation between the participant adolescent girls social skills score and happiness score before intervention. Moreover, social skills were highly positively statistically correlated with emotional intelligence, happiness, and self-esteem after the intervention. Conclusion: The social skills' training program for teenagers was successful in improving emotional intelligence, happiness, and self-esteem levels among them. Recommendations: There is a great need for ongoing monitoring of the adolescents who have participated in the social skills' training program to assist and enhance happiness, self-esteem, and emotional intelligence