Previous research on romantic secrecy found that hiding one's relationship from others predicted lower levels of relationship quality. The present research built on this work by exploring the potential consequences of relationship concealment on partners' commitment level and personal health. Study 1 found that greater secrecy was associated with reduced commitment to one's relationship, lower self-esteem, and more reported health symptoms. Study 2 tested a theoretical model of the effects of secrecy using structural equation modeling. This model was well supported and suggests that romantic secrecy (a) undermines relational commitment by means of constraining cognitive interdependence (i.e., by limiting psychological closeness to one's partner) and (b) poses a threat to partners' personal health as a result of generating negative affect (e.g., nervousness and fear). These findings indicate that romantic secrecy may have harmful consequences for both the relationship itself and the health of the partners involved.