This study examined Spanish-Welsh (in Patagonia) and Welsh-English (in North Wales) bilingual children's and adults' processing of sentences in which two noun phrases acted as arguments of a verb. The goal was to determine the relative importance of distinct cues to the identification of the subject in the bilinguals' processing of their two languages, and to explore possible crosslinguistic influence between their two languages. We provided speakers with a receptive task in which the participant heard a sentence in the given language and had to identify which of three cartoon depictions on a screen corresponded with the sentence heard. The sentences were constructed to systematically manipulate cues such as word order, prosodic stress, animacy, gender, and case marking. The results suggest some differences in performance between groups, but primarily in Welsh, not in English or Spanish. The results are discussed for their relevance to theories concerning the importance of proficiency, language balance, and acquisitional processes in bilinguals' performance in their two languages.