A digital broadcasting system and a data processing method are disclosed. Herein, additional encoding is performed on mobile service data, which are then transmitted, thereby providing robustness in the processed mobile service data, so that the mobile service data can respond more strongly against fast and frequent channel changes. The data processing method of a digital broadcast transmitting system includes the steps of forming a RS frame by grouping a plurality of mobile service data bytes that is being inputted, and performing error correction encoding in RS frame units, forming a super frame by grouping a plurality of the error correction encoded RS frame, performing row permutation in super frame units, and dividing the super frame back to RS frames, and dividing the RS frame into a plurality of data groups.