Ethylene-alpha-methylstyrene (EMS) copolymers were prepared by anionic polymerization using butyllithium and N,N,N’,N’-tetramethylethylenediamine (TMEDA) as an initiator. The C-13 n.m.r. spectra of EMS copolymers are observed and assigned mainly using two kinds of n.m.r. techniques : C-13 distortionless enhancement by polarization transfer (d.e.p.t.) and the two-dimensional incredible natural abundance double quantum transfer experiment (2D-INADEQUATE). The monomer composition, the sequence distribution in the triad level and the number-average sequence length are determined on the basis of the C-13 n.m.r. results.