A digital broadcasting system and a method for transmitting and receiving digital broadcast signal are disclosed. The method of receiving digital broadcast signal includes receiving a broadcast signal including data groups, wherein the data groups include mobile service data and signaling data including transmission parameter, wherein the transmission parameter includes a protocol version field identifying a first transmission mode or a second transmission mode, demodulating the broadcast signal, decoding the signaling data including a transmission parameter, decoding the mobile service data according to the transmission parameter included in the signaling data.