We investigated the influence of word class and translation ambiguity on cross-linguistic representation and processing. Bilingual speakers of English and Spanish performed translation production and translation recognition tasks on nouns and verbs in both languages. Words either had a single translation or more than one translation. Translation probability, as determined by normative data, was the strongest predictor of translation production and translation recognition, after controlling for psycholinguistic variables. Word class did not explain additional variability in translation performance, raising the possibility that previous findings of differences between nouns and verbs might be attributed to the greater translation ambiguity of verbs relative to nouns. Proficiency in the second language was associated with quicker and more successful production of translations for ambiguous words, and with more accurate recognition of translations for ambiguous words. Working memory capacity was related to the speed of recognizing low probability translations for ambiguous words. These results underscore the importance of considering translation ambiguity in research on bilingual lexical and conceptual knowledge.