This study reports the results of a Give-X task investigating the comprehension of ordinal and cardinal numbers in monolingual Russian-speaking children. Data collected from 36 children between the ages of 4;06 and 5;10 provided evidence that Russian learners follow the well-attested pattern for cardinal acquisition, but that children use a language-specific approach to ordinal acquisition. Lower ordinals elicited more correct responses than higher ordinals, and several cardinal subset-knowers comprehended the irregular lower ordinals vtoroj 'second' and tretij 'third'. This suggests that Russian-speaking children initially learn ordinals lexically, unlike English- and Dutch-speaking children, who have previously been shown to use a rule-based approach. The authors argue that this is explained by the irregularity of the Russian ordinal system, which makes the threshold for rule-learning too high for an initial rule-based approach. Future research should clarify whether lexical learning of ordinals leads to the same underlying knowledge of ordinals as rule-based learning does.