This book explores how living in a second language environment can change an individual’s pronunciation in their first language – sometimes so much that they start to sound foreign in their native language. Written in accessible chapters, it explains what changes happen to segments and prosody, how listeners perceive these changes, and why some people are affected more than others. It also looks at whether such changes are permanent, how they relate to second language learning, and what they mean for identity and the concept of the 'native speaker'. A go‑to resource for students, teachers, and anyone interested in how our first language accent can shift in a new language environment.