A digital broadcasting system and a data processing method are disclosed. A receiving system of the digital broadcasting system includes a receiving unit, a demodulator, an equalizer, a block decoder, and a RS frame decoder. The receiving unit receives a broadcast signal including mobile service data and main service data. The mobile service data may configure a RS frame. The RS frame includes at least one data packet for the mobile service data, RS parity generated based on the at least one data packet, and CRC checksum generated based on the at least one data packet and the RS parity. The demodulator converts RS frame data included in the broadcast signal received by the receiving unit into a baseband RS frame data. The equalizer performs channel equalization on the data demodulated by the demodulator. The block decoder performs symbol-decoding on the data channel-equalized by the equalizer in block units. The RS frame decoder performs CRC-decoding and RS-decoding on the decoded mobile service data in RS frame units, thereby correcting errors occurred in the mobile service data within the RS frame.