Infant sleep problems have been found to be related to child, parent, and family difficulties in both the short and long term. Behavioural interventions have been shown to be important for reducing and preventing these associated problems. As the primary caregivers of infants, parents are key figures in providing information about their children to clinicians and researchers. They also determine whether and when to seek treatment for infant sleep problems, and how interventions are implemented. However, little is known about how parents perceive infant sleep problems, a factor that is important in parental decisions for seeking infant sleep interventions. Thus, it is vital to gain further insight into parents’ understanding of infant sleep problems. Guided by the transactional model of infant sleep developed by Sadeh, Tikotzky, and Scher (2010), this study explores the relationship between child age, mothers’ perception of infant sleep problems for their own children, mothers’ sleep-based attribution, and mothers’ assessment of infant sleep problems for children in a scenario. Results from a sample of 878 mothers of children 6 to 23 months of age showed that child age, mothers’ perception of a sleep problem for their own children, and sleep-based attributions were significant predictors of mothers’ assessment of infant sleep problem for scenario children. With regard to child age, mothers were more likely to give more responsibility for sleep behaviours to and to assess an infant sleep problem for older infants than younger infants. When mothers thought their own children had a sleep problem, this seemed to be related to their global perceptions of infant sleep behaviours, as they were also more likely to identify an infant sleep problem for a scenario child. Lastly, mothers attributed greater child responsibility (higher child-centered locus, controllability, and intentionality) and parent-centered locus for good sleep and less so for negative sleep. The implications of these findings and future directions are discussed.