This book explores the process of acquiring UK citizenship and investigates how the naturalisation process is experienced, with an explicit focus on language practices. This ethnographically-informed study focuses on W, a Yemeni immigrant in the UK, during the final phase of the citizenship process. In this time, he encounters linguistic trials and tests involving the Life in the UK citizenship test, community life, ESOL (English for Speakers of Other Languages), adult education and the citizenship ceremony. The richness of linguistic data featured in this book allows for a nuanced portrayal of the complexities of becoming a citizen. This is especially so in the context of the UK's assimilationist form of citizenship which is reflected in the introduction of a citizenship test within a broader socio-political climate. Becoming a Citizen offers a detailed analysis of the linguistic process of naturalisation in the the UK and is relevant to scholars working in sociolinguistics, language policy, migration studies and ethnographic research.