A digital broadcasting system and method of processing data are disclosed. Herein, a method of processing data of a transmitting system includes generating a service informative null packet including service-related information of mobile service data, and multiplexing a plurality of main service data packets, a plurality of mobile service data packets, and a plurality of service informative null packets, and transmitting the multiplexed data packets to at least one transmitter located in a remote site. The digital broadcasting system and method of processing data may enhance receiving performance of a receiving system by performing additional encoding on mobile service data and by transmitting the processed data to the receiving system.