This article investigates the relationship between third person singular present tense agreement morphemes, copula "is" and verb-"s", at 2;00 and 2;03. Language samples from 60 children at 2;00 were analyzed for the productivity of copula "is" as measured by the number of different morphemes preceding "is" in children's sentences. Samples at 2;03 were analyzed for the number of different verb stems affixed with -"s" or marked with verb past inflection. Concurrent control measures of vocabulary and MLU were obtained at 2;03. Two hierarchical multiple regressions were performed to determine whether there was a relationship between 2;00 copula "is" and 2;03 verb inflection. Each regression had a different 2;03 verb inflectional category, verb-s or verb past, as its dependent variable. The results of the verb-"s" regression showed that both MLU and copula "is" productivity accounted for significant portions of unique variance in 2;03 verb-"s" productivity. In contrast, the results of the verb past regression revealed that only MLU accounted for a significant amount of variance. These data indicate that the grammatical features connecting copula "is" and verb-"s" emerge soon after the second birthday.