Prior research on privacy disclosure primarily focuses on conscious factors leading to intentional disclosure. In this study, we identify two unconscious factors, i.e., the habit of self- disclosure and the impulse of self-disclosure, which lead to users’ privacy disclosure behavior in social networking sites (SNS). We contribute to the existent literature by investigating the effects of these two factors on privacy disclosure behavior in SNS and examining a contingent factor for the effects of these two unconscious factors. Our results reveal that both habit and impulse have significant effects on privacy disclosure in SNS. The effects of habit and impulse are moderated by users’ privacy self-efficacy. Particularly, privacy self-efficacy weakens the effects of impulse on self-disclosure but strengthens the effect of habit on self-disclosure.