Partially melted metallocene-based isotactic polypropylene (m-iPP), which was preoriented with a high degree of molecular orientation and a shish-kebab structure, was annealed at various temperatures and isothermally crystallized at 130 degrees C. The melting and crystallization process was examined using synchrotron wide-angle X-ray diffraction, small-angle X-ray scattering, and differential scanning calorimetry. For the m-iPP samples annealed at relatively low temperatures, lamellar thickening, lateral growth, and a decrease in the gamma-crystal fraction occurred. Because of parallel evolution of alpha- and gamma-crystal growth in the limited crystallizable melt volume, the fraction of gamma-crystals was very low. Furthermore, topological constraints in the melt dominate the chain flux in crystal evolution; the chains are consumed by the thickening lamellae and lateral growth, forming alpha-crystals with parallel chains in the unit cell. For the m-iPP samples isothermally annealed at medium annealing temperatures, the increase in the amount of crystallizable melt caused the gamma-crystal fraction to increase. A shish-kebab (alpha-crystals) structure with high thermal stability and a newly formed macro-unoriented structure coexisted in the final sample. After annealing at high temperatures, at which no crystals survived, gamma-crystal formation was greatly favored; this was attributed to the nature of m-iPP molecules and their dynamic behavior at 130 degrees C. Because of the lack of oriented nuclei, randomly oriented lamellae were formed. On the basis of the structural cooperative changes at different scales, the morphological features at different annealing temperatures were proposed.