A receiving system and a data processing method are disclosed. The receiving system includes a receiving unit, a demodulator, a first handler, a second handler, and a third handler. The receiving unit receives a broadcast signal comprising fast information channel (FIC) data, transmission parameter channel (TPC) data, and mobile service data packetized into an RS frame. The demodulator demodulates the broadcast signal. The first handler configures an ensemble from the RS frame, so as to acquire first signaling information including access information of the mobile service. The second handler receives second signaling information of the mobile service, so as to acquire content identification information of a second data type from the received second signaling information. And, the third handler extracts a mobile service identifier and a content identifier of a first data type from the first signaling information and constructs content identification information of a second data type.