Parents may wait to talk to their teens about sexuality until they believe their child is in a romantic relationship. To examine this, telephone surveys were conducted with 1069 parents of adolescents. Measures assessed parents' perception of teens' romantic involvement and parent-child communication about several sexuality topics. Multivariable regression models determined the odds of talking about each topic among parents who reported their teen had been in a romantic relationship compared to those who did not. Most parents reported talking at least a moderate amount about some sex-related topic. Parents who believed their teen had been romantically involved were more likely to have discussed most of the topics examined here (ORs=1.64-2.56). For some topics, associations were more pronounced among parents of younger teens. Findings suggest that parents may miss important opportunities to influence behavior, and should initiate conversations about sexuality before they believe their child to be romantically involved.