Abstract Introduction: This study aims to find out an overview of the effect of family aspects on premarital sexual behavior at risk of unintended pregnancy among adolescents at Pulogadung Sub-District Community Health Center, East Jakarta. Method: This is a qualitative study, using purposive sampling technique. Data were collected using in-depth interview technique and document review. The sample consisted of 16 informants, consisting of 4 pregnant adolescents as key informants, 8 parents, and 4 peers of pregnant adolescents. Results: The results of this study revealed that the family aspect: communication between adolescents and their parents was not quite open and disharmonious. In addition, establishing communication with peers occurred very well especially regarding the problems experienced by the adolescents as one that causes them to obtain information and follow deviant behavior. Conclusion: Promiscuity in adolescents, lack of attention and communication from family and the environment, and access to information are the most important aspects of premarital sexual behavior resulting in unintended pregnancy among adolescents. This study recommends the importance of activating the Youth Care Health Program and developing Information, Education, Communication (IEC) content in the reproductive health curriculum for adolescents.