Existing research shows that intrusive behavior has detrimental consequences for relationships. Surprisingly, little is known about why close relationship partners snoop. This study examined why romantic partners engage in intrusive behavior among newlywed couples in the Netherlands. As predicted, the results showed that perceiving a lack of partner disclosure is linked to intrusive behavior, and importantly, that trust moderates this link. Only when people did not trust their partner were their perceptions of partners' low disclosure associated with intrusive behavior. When people trusted their partner, perceived partner disclosure was not associated with intrusive behavior. These results help to explain why people snoop and highlight the importance of trust as a powerful protective buffer against intrusive behavior in close relationships. © 2010 IARR.