Strategies for structural and quantitative analysis of unknown heterogeneous block copolymers employing solid-state C-13 magic-angle spinning (MAS) NMR techniques are presented. Combinations of standard single-pulse, cross-polarization, cross-polarization-depolarization, and SEMUT spectral editing MAS experiments enable efficient separation, identification, and quantitation of resonances from mobile as well as immobile phase constituents of heterogeneous polymers. The utility of these techniques for structural and quantitative analysis of complex polymers is demonstrated for three block copolymers, initially of unknown structure and composition. The three samples investigated here have been identified as polypropylene/polyethylene/ethylene-propene-diene rubber (PP/PE/EPDM), polyethylene/ethylene-propene rubber (PE/EPR), and polystyrene/polyethylene/butadiene rubber (PS/PE/BR).