The present invention provides a method of processing data in digital broadcasting system. The method includes receiving a broadcast signal including mobile broadcast service data and main broadcast service data, wherein the mobile broadcast service data configures a RS frame, and wherein the RS frame includes at least one data packet corresponding to the mobile broadcast service data, an RS parity generated based upon the at least one data packet, and a CRC checksum generated based upon the at least one data packet and the RS parity, performing CRC-decoding and RS-decoding on the RS frame, thereby correcting errors occurred in the corresponding mobile broadcast service data, extracting video data from the mobile broadcast service data, and decoding the extracted video data, wherein the video data includes data of a base layer and data of an enhanced layer and wherein the enhanced layer has a spatial resolution or an image quality different from that of the base layer.