Throughout its history, Iran has been a richly multilingual nation, with documented evidence reaching back nearly three millennia. Today, estimates of the number of languages spoken in modern Iran vary, with numbers ranging from fifty-four to seventy-six living languages. This chapter presents a general description of societal bilingualism, how bilingual communities come about, the relationship between language and identity in multilingual contexts, and how best to describe the kind(s) of bilingualism found in Iran, including the use of English. The chapter then turns to bilingualism in Iran from a historical perspective, with the goal of understanding why there are so many languages in present-day Iran. Finally, it addresses the status of English in pre- and post-revolutionary Iran and issues of language maintenance.