The CC bond dissociation energy in the cyanoethynyl radical (C3N) is predicted using various coupled-cluster and composite energy methods. The singles and doubles coupled-cluster method that includes a perturbational correction for connected triple excitations, denoted CCSD(T), has been used with a variety of basis sets. The largest basis set used is the cc-pVQZ that includes g functions. By extrapolating the CCSD(T)/cc-pVQZ results to the basis set limit, the best estimate of the CC bond dissociation in C3N is 128.8 +/- 0.9 kcal mol(-1).