A digital broadcasting system and a method of processing data are disclosed. The method of processing data of a transmitting system includes generating signaling information including service-related transmission parameters of mobile service data, packetizing the generated signaling information to a predetermined data packet format, primarily multiplexing the packetized signaling information and a mobile service data packet including the mobile service data, and secondarily multiplexing the primarily multiplexed data packets and a main service data packet including main service data, thereby transmitting the secondarily multiplexed data packets to at least one transmitter located in a remote site.