Languages vary idiosyncratically in the sets of referents to which common nouns are applied. To use nouns as a native speaker would, second language learners must acquire language-specific naming patterns, not merely a language-to-language correspondence. We asked second language learners to name household objects in English and in their native language, to judge the objects' typicality with respect to English names, and to provide naming strategy reports. The least experienced learners' naming and typicality judgments diverged substantially from native responses. More experienced learners improved, but even those with the most extensive experience retained some discrepancies from native patterns. Time spent immersed in an English-speaking environment was a better predictor of performance than years of formal instruction. Discrepancies do not appear to be due to direct mapping from the learner's own language. We discuss how incomplete lexical knowledge may affect second language performance and the implications for models of second language lexical development.