With over 6,000 languages spoken worldwide and a history of colonialism and nationalism, people commonly have proficiency in the indigenous language of a region or of a non-localized minority group (ethnic, religious, Deaf, etc.), as well as in a national language. Monolingual or multilingual, dictionaries are products of their sociolinguistic environment. Though dictionaries may be treated by the public as a way to make the language into a static, bounded entity, lexicographers must contend with a lack of clear boundaries as to where their object languages end, given that their language communities include multilingual speakers. Despite this widespread bilingualism, language contact has not been thoroughly treated in English-language literature on lexicography. This chapter synthesizes the different ways that language contact manifests itself through dictionaries. It demonstrates that the asymmetry between the social standing of languages in contact manifests itself in the production and composition of dictionaries. It explores the difficulties that come with establishing the boundaries of the object language, with particular attention to Creoles and signed languages. The chapter details the problems that such difficulties pose to dictionaries of foreignisms. We conclude with an exploration of how language contact can and should inform the future of dictionary creation.