Number sense skills provide the foundation for the acquisition of higher order mathematical skills and concepts. However, there is disagreement over the definition of number sense, the specific skills that make up the construct, and the psychometric properties of measures used to assess these skills. In the current study, 10 brief tasks hypothesized to assess facets of number sense were administered to a sample of 218 kindergarten students. Exploratory factor analysis demonstrated that a two-factor model best fit the data, with the first factor consisting of number-related skills and the second factor consisting of rapid naming skills. Implications for conceptualizing the number sense construct and measuring number sense skills in young children are discussed. (Contains 5 tables and 1 footnote.)