The Raman spectrum of the polydiacetylene, poly( 1,6-bis[N-carbazolyl]-2,4-hexadiyne), has been reexamined and analyzed in terms of the resonant interaction of backbone and side-group vibration modes. Fourier transform infrared Raman spectra have been recorded for partially and fully polymerized samples. These data complement earlier studies of the resonance-Raman spectra of partially polymerized crystals conducted at low temperatures. The multipeaked spectrum, which is observed in the vicinity of the stretching vibration of the backbone carbon double bond, is analyzed utilizing these results. A model that incorporates the resonant interaction of the carbon double-bond mode with three vibrational modes of the carbazolyl side groups is shown to provide a good fit to the available experimental data.