We completed a systematic review of literature related to parent knowledge of children's sleep, to determine how much parents know about typical child sleep and symptoms related to sleep problems in childhood and how parent knowledge has been assessed. We also examined whether relationships have been reported between parent knowledge of children's sleep, parent education, child sleep problems, sleep duration, and sleep hygiene. An extensive literature search of five electronic databases was conducted, and of 615 articles identified, eight met inclusion criteria for review: four descriptive studies and four educational interventions. These studies varied considerably in the number of items included in scales, the specific content measured, the response scales used, and the populations included, limiting the conclusions that could be drawn across studies. In general, parent knowledge of child sleep was poor. Greater accuracy was reported for items pertaining to healthy sleep practices at sleep onset and daytime symptoms, in comparison with items pertaining to child sleep problems during the night. More knowledgeable parents were more likely to report that their children exhibited healthy sleep practices; associations with sleep duration were mixed. Small interventions demonstrated an increase in parental knowledge in the short-term, but effects were not maintained at follow-up. Future work is needed to clarify relations between parental knowledge and child sleep, and to design and evaluate effective methods of promoting education about child sleep in a range of parent populations. The further development of validated tools to assess parent knowledge of child sleep will be required to underpin this work.