Purpose: Elementary-age dual language learners (DLLs) from Spanish-speaking homes in the United States are often characterized as at risk for low vocabulary in both Spanish and English. This longitudinal study examined conceptually scored receptive and expressive vocabulary development among DLLs from Spanish-speaking, low-income homes and investigated patterns of language responses on the conceptually scored measures. Method: DLLs in kindergarten and second grade (N = 118) attending school in the Southeast region of the United States were followed for three consecutive academic years and assessed on measures of receptive and expressive conceptually scored vocabulary. Results: Individual growth modeling, using raw scores, revealed positive vocabulary growth over time, with "above average" performance relative to national norms. However, initial conceptually scored receptive vocabulary scores were higher than conceptually scored expressive vocabulary scores. Furthermore, DLLs' conceptually scored receptive--but not expressive--vocabulary rate of growth was more rapid compared to national norms. Finally, DLLs' patterns of language responses revealed a shift toward more English over time, but Spanish continued to be used through fourth grade. Conclusion: Results contradict deficit-driven views about DLLs' vocabulary skills and underscore the utility of conceptually scored vocabulary measures to assess vocabulary development among elementary-age DLLs to more comprehensively account for the linguistic assets they bring to learning.