The influence of phonological similarity on bilingual language processing was examined within and across languages in three experiments. Phonological similarity was manipulated within a language by varying neighborhood density, and across languages by varying extent of cross-linguistic overlap between native and non-native languages. In Experiment 1, speed and accuracy of bilinguals' picture naming were susceptible to phonological neighborhood density in both the first and the second language. In Experiment 2, eye-movement patterns indicated that the time-course of language activation varied across phonological neighborhood densities and across native/non-native language status. In Experiment 3, speed and accuracy of bilingual performance in an auditory lexical decision task were influenced by degree of cross-linguistic phonological overlap. Together, the three experiments confirm that bilinguals are sensitive to phonological similarity within and across languages and suggest that this sensitivity is asymmetrical across native and non-native languages and varies along the timecourse of word processing.