Negative strand RNA viruses have a unique mechanism of replication. Their genome is a single strand RNA that has to be transcribed as soon as the virus enters the host in order to carry out viral replication. As a result, a viral-specific RNA polymerase is packaged in the virion and is ready for transcription after virus entry. This novel replication mechanism dictates the assembly and RNA synthesis of negative strand RNA viruses. In recent years, many discoveries have been made with regard to the entry, replication and assembly of this class of viruses. This book will present updated coverage of the fundamental knowledge about negative strand RNA viruses.