The techniques of wide-angle X-ray diffraction, infra-red spectroscopy and differential scanning calorimetry were used to characterize the glass transition and crystallization behavior of freeze-dried isotactic polystyrene (iPS) derived from dilute solutions. It was found that there is a concentration boundary for the original solution: below the boundary, the freeze-dried IFS samples are poorly crystallized but the chains are in a highly ordered 31 helix state; above the concentration boundary, the freeze-dried iPS is in a completely disordered amorphous state.