Although children may productively use concrete nouns after limited exposure, complete mastery of adult-like patterns of noun usage can take up to 14 years. We evaluated whether a transition from universal to language-specific naming is part of the refinement in later lexical development, and we compared how this refinement plays out in monolingual versus bilingual children. We collected free naming data for pictures of nearly 200 household containers from 499 Belgian children, aged 5 to 14, and adults, raised with either (a) only French, (b) only Dutch, or (c) both French and Dutch. Both monolingual and bilingual 5-year olds produced largely shared naming patterns, and for both groups, naming patterns became more language-specific and also more consistent within-language over time. However, monolinguals and bilinguals diverged in some aspects of their developmental profiles. Monolinguals started to introduce language-specificities to their naming pattern beginning at age 8, but differentiation between languages did not emerge for bilinguals until age 12. Consensus on name choice increased across ages for both groups, but bilinguals showed more consensus at all ages, reflecting smaller vocabularies and less differentiation. Thus monolingual and bilingual children follow a similar trajectory from shared to language-specific patterns of word use, but bilinguals differentiate later and for only some words. This study demonstrates that a transition from shared to language-specific naming is a key aspect of later lexical development, but the developmental course differs in detail between monolingual and bilingual children.