Facebook, Twitter, and Instagram are the most often and most widely used social-media sites, especially in Indonesia. The number of social-media users is increasing every year, accompanied by increased risks. One of those risks is to the security and privacy of users, as shown by the user-data leak experienced by Facebook in 2018. These issues led the authors to conduct research relating to the influence of privacy concerns, trust, and user awareness on the readiness to share personal information via social-media sites. A research model was developed based on several hypotheses. The research model was confirmed, and experiment was conducted from 340 social-media users through a questionnaire-based online survey over a period of 2 months. To confirm the structural model used in this research, reliability and validity analyses were performed. Structural equation model (SEM) analysis was used to detect relationships among constructs in the research model. The results of this research show that user awareness, trust, and privacy concerns have a positive and significant effect on sharing personal data on social media. Then we discussed the implications of our results for policy-making, practice, and future research.