Background: Although there is debate on the effectiveness of youth-focused abstinence education programs, research confirms that parents can influence their children’s decisions about sexual behavior. To leverage parent-based approaches to adolescent sexual health, the U.S. Department of Health and Human Services launched the "Parents Speak Up National Campaign" (PSUNC) to encourage parent-child communication about sex. Previous experimental studies have found the campaign to be efficacious in increasing parent-child communication. But to date, the actual reach of the campaign and its real-world effectiveness in promoting parent-child communication has not been established. The present study addresses this gap. Method: The authors surveyed 1,804 parents of 10- to 14-year-old children from the nationally representative Knowledge Networks online panel. The survey included questions about parents' awareness of PSUNC ads and parent-child communication behaviors. The authors also analyzed market-level data on campaign gross rating points, a measure of market-level intensity of PSUNC advertising in the United States. Multivariate regressions were used to examine the association between PSUNC exposure and a three-item scale for parent-child communication. Results: Overall, 59.4% of parents in the sample reported awareness of PSUNC. The authors found that higher market-level PSUNC gross rating points were associated with increased parent-child communication. Similar relationships were observed between self-reported awareness of PSUNC and increased frequency of communication and recommendations to wait. These associations were particularly strong among mothers. Conclusions: This study provides the first field-based data on the real-world reach and effectiveness of PSUNC among parents. The data support earlier experimental trials of PSUNC, showing that the campaign is associated with greater parent-child communication, primarily among mothers. Further research may be needed to develop additional messages for fathers. (Contains 1 figure and 4 tables.)