Research indicates that children do not typically understand the connection between counting and cardinality for several months after learning to count, yet parents speak to 3-year-olds as though they already understood the significance of counting. The present research was designed to investigate mothers’ awareness of the discrepancy between children's procedural and conceptual mastery of counting. In Study 1 mothers of a hundred 3- to 41/2-year-olds completed an anonymous questionnaire asking them to anticipate how their child would respond to a series of real-life vignettes based on widely used experimental measures of cardinal understanding. Most anticipated that their child, irrespective of age, would (1) understand the significance of the last word of a count, and (2) be able accurately to give a specified non-subitizable number of objects. Comparison with the performance of 54 children from the same local population supported the hypothesis that parents overestimate children's understanding of the cardinal significance of counting. Mothers reported a range of impromptu number-related activities in which their child had recently participated at home; most of these involved simple procedural counting. In Study 2, 35 mothers of 3- to 41/2-year-olds completed a modified questionnaire concerning procedural aspects of counting as well as cardinality; their responses were then compared with the performance of their own children. Again, mothers overestimated their children's cardinal understanding, but this was shown not to be a result of a general tendency to overestimate their counting abilities. It is suggested that preschoolers’ counting generally occurs during joint activities in which caregivers may be unaware of the support that they provide, and, provided that the jointly executed count procedures are error-free, parents implicitly assume a ‘common knowledge’ regarding the cardinal significance of counting.