Prior research has shown possible relations among nonword repetition (NWR), vocabulary, and phonological processing skills in children with and without language impairment. This study was designed to investigate whether relationships would differ for students with primary language impairment (PLI) and typical language (TL) and whether they would shift across the school-age years, with implications for setting intervention priorities. NWR performance was compared for school-age students with PLI (n = 36) and TL (n = 36), matched for age, sex, race/ethnicity, and home language experience at three grade level bands (grades 1-2, 3-5, and 6-12). Both groups also completed tests of vocabulary awareness and phonological awareness to investigate them as predictors of performance on the NWR task. The two groups differed significantly with large effect sizes on the NWR task, as well as on vocabulary awareness and phonological awareness tasks. Regression analyses supported different predictive models for students with TL and PLI, with vocabulary awareness predicting significant variance in NWR for the TL students, but not for those with PLI. Conversely, phonological awareness, but not vocabulary awareness, predicted NWR for the students with PLI. Controlling for age did not change the regression models. Results support a view that phonological processing difficulties may function as a specific limiting factor for students with PLI, influencing their ability to learn new vocabulary as well as vice versa. These results have implications for designing treatment aimed explicitly at helping children connect sublexical aspects of word structure knowledge with word meaning.