Multilevel coded modulation is described as an alternative to Ungerböck’s Trellis-Coded Modulation, where subset labels are protected by individual codes, thereby representing a Generalized Concatenated (GC) structure. Multilevel codes usually come with multi-stage decoding, however, the full trellis decoding is also shown. The optimum design based on subset capacities is derived and also structures to ensure rotational invariance. Bit-interleaved coded modulation together with Gray coding concludes the chapter.