What shapes and magnitude can language loss have in East Asian endangered languages? How does it differ with regards to the languages' historical development and sociolinguistic environment? This book surveys a number of minority and, in most cases, endangered languages spoken in China, Japan, Taiwan, and Russia which all face, or have faced in their recent history, loss of language features. The contributions in this publication present you with different cases of obsolescence attested throughout East Asia and highlight how this process, though often leading back to common causes, is in fact a multifaceted reality with diverse repercussions on grammar and linguistic vitality.