The stable conformation and the sequential order of isotactic polystyrene (iPS) gel have been investigated by solid-state high-resolution C-13 NMR and infrared spectroseopies. The methylene resonance line in the solid-state high-resolution C-13 NMR spectrum is very sensitive to the conformation. The same chemical shift observed for both the gel and crystalline form demonstrates the molecular conformation formed in the gel takes a 3/1 helix. The process of conformational ordering during the gelation process of the iPS/CS2 system has been followed by infrared spectra, In addition to the bands characteristic for a 3/1 helix, the gel-specific bands were observed. The 983 cm(-1) band is a typical crystallization-sensitive band due to the ring out-of-plane mode with no relation to the main chain mode. This band increased in intensity for the crystalline form, but not for the gel. From the isotope dilution analysis using partially deuterated iPS, this band does not come from either inter- or intramolecular interaction but the disorder of the C(skeletal)-C(ring) axis. This suggests that the solvent molecules are incorporated between polymer chains. The temperature dependence of the absorption intensity has been quantitatively interpreted by a simple statistical model. The trans-gauche regular sequence formed in the iPS/CS2 gel was estimated to be longer than five turns of the 3/1 helix.