Young adult learning about human papillomavirus (HPV) infection has lately received increased attention in health education literature. HPV's mode of transmission, lengthy dormancy, and link to cervical cancer make the potential dangers of the infection particularly relevant for young adults. However, sexual health education in the USA is deeply intertwined with a moral debate about the appropriateness of talking openly about sexual behaviour with young people. The moral debate has extended to HPV prevention and may, in and of itself, have an impact on learning. Research suggests that constructing accurate scientific knowledge can be difficult for learners due to extra-rational factors such as personal values and motivation. The current study found that, in the context of HPV prevention, extra-rational factors associated with conventional moral beliefs may moderate the relationship between intent to learn and knowledge construction, resulting in errors in understanding among young adults about HPV infection. (Contains 4 tables and 3 figures.)