A system and method for channel interleaver and layer mapping in a communications system with spatial multiplexing are provided. A method for transmitting information over M layers, where M is a positive integer value representing a number of spatial layers, and M≧2, includes receiving at least one codeword to transmit, grouping a plurality of symbols in the at least one codeword into M groups, mapping the M groups to the M layers, and transmitting the M layers. The at least one codeword includes the plurality of symbols, and each symbol includes two or more code bits.