Generalized social trust – trust in unknown others – is essential for cooperation between strangers and therefore lays the foundation for a well-functioning society. With continued immigration, scholars and pundits have questioned whether trust can be maintained in the face of an increasingly ethnically diverse populace. Yet, despite an abundance of analyses, we have only fragmented evidence on this question at best. In response to this, the book project seeks to systematically address the claim regarding the consequences of immigration for social trust both theoretically and empirically.