This chapter introduces chief postulates common to usage-based (UB) approaches to language. The UB approach maintains that speakers’ experiences with language shape how language is stored. Experiences with specific words and word combinations in particular linguistic, discursive, and social contexts accrue in memory and subsequently contribute to patterns of variability evident in speech productions. Usage-based approaches regularly consider independent effects on lexical representations of decontextualized prior probabilities (e.g. phone/word/bigram frequencies, type frequencies), and, increasingly, contextually informed counts (e.g. lexical items’ cumulative exposure to conditioning effects of the production contexts, phone/word probabilities) are considered. This chapter offers an overview of studies exploring the connection between usage patterns and bilingual sound systems as well as studies exploring evidence of interlingual influence arising from bilingual lexical storage (schematic ties in memory). The chapter suggests potential avenues for future UB research into bilingual phonetics and phonology.