Knowledge about the smallest meaningful units of language, morphemes, is crucial for vocabulary and reading comprehension. This meta-analysis of 43 studies examined differences in morphological knowledge in the societal language between language-minority and language-majority children. There was a moderate to large mean group difference in morphological knowledge in favor of the language-majority children. Studies that examined inflectional knowledge (walk-walked, rose-roses) reported larger differences than studies that examined knowledge of derivations (coexist, serious) and compounds (bluebird, highlight). Studies that used oral tests and tests of expressive language reported larger differences than studies that used written tests and tests of receptive language. These findings show that morphology is an area of weakness in language-minority children. Paired with the evidence that morphological instruction improves general language ability and reading comprehension, the results suggest that morphology could be an essential component in language interventions for language-minority children.