Scholars of language ideology have encouraged us to reflect on and explore where social categories come from, how they have been reproduced, and whether and to what extent they are relevant to everyday interactional practices. Taking up on these issues, this book focuses on how ethnicity has been semiotically constructed, valued, and reproduced in Indonesia since Dutch colonial times, and how this category is drawn upon in everyday talk. In doing so, this book also seeks to engage with scholarship on superdiversity while highlighting some points of engagement with work on ideas about community. The book draws upon a broad range of scholarship on Indonesia, recordings of Indonesian television from the mid-1990s onwards, and recordings of the talk of Indonesian students living in Japan. It is argued that some of the main mechanisms for the reproduction and revaluation of ethnicity and its links with linguistic form include waves of technological innovations that bring people into contact (e.g. changes in transportation infrastructure, introduction of print media, television, radio, the internet, etc.), and the increasing use of one-to-many participation frameworks such as school classrooms and the mass media. In examining the talk of sojourning Indonesians the book goes on to explore how ideologies about ethnicity are used to establish and maintain convivial social relations while in Japan. Maintaining such relationships is not a trivial thing and it is argued that the pursuit of conviviality is an important practice because of its relationship with broader concerns about eking out a living.