Research on parental knowledge and positive adolescent adjustment suggests that more accurate levels of the former increase the likelihood of the latter. Despite a significant body of literature correlating adolescent pornography use with negative adolescent adjustment, however, only a handful of studies have compared parents’ beliefs about their children’s pornography use with adolescents’ reports and just a few of these have been carried out in the U.S. The present study employed national probability data gathered from 614 parent–adolescent dyads in the U.S. as a further step toward bolstering this important area of parent–child research. Parents were 44.78 years old on average (SD = 7.76). Mothers comprised 55.80% of parents (fathers were 44.20%). Children were 15.97 years old on average (SD = 1.38). Daughters comprised 50.20% of children (sons were 49.80%). Boys were more likely to report pornography use and learning across a range of pornography genres and sexual domains. Parents accurately estimated the direction of many of these gender differences, but still consistently underestimated both sons’ and daughters’ exposure to and socialization from pornography. Interestingly, although parents were more likely to believe that sons than daughters had viewed and learned from pornography, their degree of underestimation was larger for sons. Mothers’ and fathers’ beliefs were consistently indistinguishable at the main effect level and interacted with child gender in only one instance. Results are discussed in relation to the moral panic and risk underestimation perspectives on youth and media effects.