This study aimed to describe the relationship between character education and knowledge about sex and sexually transmitted diseases to the behavior of promiscuity among teenagers. This study uses quantitative methods. The technique of collecting data using questionnaires, observation and documentation. Data analysis technique uses statistical analysis descriptive and inferential statistical analysis. The results showed that; a) the character education has a significant relationship with the behavior of free sex teen, b) knowledge about sex and sexually transmitted diseases have a significant relationship with the behavior of free sex teen, c) character education and knowledge about sex and sexually transmitted diseases collectively have relationship with the behavior of teenage promiscuity. Conclusion of the study 1) the character education has a significant relationship with the behavior of promiscuity teenagers, in this case the better education of character it is increasingly avoid behavior promiscuity, 2) knowledge about sex and sexually transmitted diseases have a significant relationship with the behavior of promiscuity teenagers, in this case the better knowledge of adolescents about sex will increasingly avoid promiscuous behavior, 3) Education of character and knowledge about sex and sexually transmitted diseases collectively have a relationship with the behavior of promiscuity. Thus it can be interpreted that the better the education of character and better knowledge about sex and sexually transmitted diseases, it is increasingly avoid behavior promiscuity Keywords: Character Education , Knowledge of free sex and sexually transmitted penyakt , Behavior of free sex teen