A series of poly(ferrocenyldimethylsilanes) (PFS) with narrowmolar mass distribution wereprepared via anionic ring-opening polymerization. The thermalbehavior and morphology of thesematerials were investigated. Differential scanning calorimetry(DSC) experiments showed multiplemelting endotherms upon heating after isothermal crystallization.Melting of thin lamellae andrecrystallization into thicker lamellae accounted for these multipletransitions. Wide-angle X-rayscattering (WAXS) showed that the crystal structure remained unchangedduring heating. An increasein the long-period observed with temperature-dependent small-angleX-ray scattering (SAXS) supportedthe assumption that lamellar thickening occurs. Thesemicrystalline polymers showed a melting behavioras described by the Hoffman−Weeks equation, leading to an equilibriummelting temperature of 143 °C.