The aim of this longitudinal study is to evaluate 3 views on the relationship between nonword repetition and vocabulary: (i) the storage-based view that considers nonword repetition, a measure of phonological storage, as the driving force behind vocabulary development, (ii) the lexical restructuring view that considers improvements in nonword repetition as the result of vocabulary growth, and (iii) the "combined" view that assumes that both storage-based learning and lexical restructuring play a role, resulting in reciprocal relationships between nonword repetition and vocabulary during language development. Data are analyzed from 471 monolingual Dutch children who performed tasks assessing nonword repetition and vocabulary at yearly intervals, from ages 2 to 5. Latent Change Score (LCS) modeling of Item Response Theory-scaled scores was used to investigate the relationships between nonword repetition and vocabulary growth over time. Additionally, the statistical techniques used in earlier work-cross-lagged and latent growth modeling-were applied to see whether the results changed as a function of the analytical technique used. Results from a bivariate LCS model showed positive reciprocal influences from nonword repetition on vocabulary between 2 and 5 years. Such positive cross-influences also emerged from the cross-lagged and latent growth models. Predictive relationships from vocabulary to nonword repetition were stronger than vice versa. These results indicate that both storage-based learning and lexical restructuring play a role in vocabulary learning, at least in early stages of language development, with the clearest support found for lexical restructuring. (PsycINFO Database Record (c) 2019 APA, all rights reserved).