In a previous study, Mix et al. (2016) reported that spatial skill and mathematics were composed of 2 highly correlated, domain-specific factors, with a few cross-domain loadings. The overall structure was consistent across grade (kindergarten, 3rd grade, 6th grade), but the cross-domain loadings varied with age. The present study sought to replicate these patterns. Using the data from Wave 1 (n = 854) and data collected from a 2nd sample of kindergarten (n = 251), 3rd-grade (n = 247), and 6th-grade students (n = 241) with the same measures as in Wave 1, we carried out a multigroup confirmatory factor analysis to compare the 2 waves. We also completed several analyses of the Wave 2 data alone. The overall pattern obtained in Wave 1-2 highly correlated domain-specific factors--was clearly replicated in Wave 2. However, more subtle effects involving cross-domain loading were only partially replicated and generally appear fragile and context-specific. In Wave 2, we also included 2 new measures (i.e., proportion matching and fraction identification) that were analyzed in a separate model. Including these new measures did not change the overall pattern of factors and domain-specific factor loadings but did alter some of the cross-domain loadings. [This article was published in "Journal of Cognition and Development" v18 n4 p465-492 2017 (EJ1155171).]