The present study focuses on the crystallization behavior and structure formation of isotactic polypropylene (iPP) containing polymeric nucleating systems. Poly(vinyl cyclopentane) (PVCP) and poly(vinyl cyclohexanе) (PVCH) were pre-polymerized on the catalyst particle before propylene polymerization. Non-isothermal crystallization experiments were performed by standard differential scanning calorimetry (DSC) and by fast scanning chip calorimetry (FSC) at cooling rates in the range from 10−1 to 103 K/s. Wide angle X-ray scattering (WAXS) was employed to collect information regarding the crystal structure of samples with a specific cooling history prepared in FSC. Both nucleating agents, PVCP and PVCH, led to acceleration of crystallization and increase of the temperature range of α-phase crystallization of iPP. Most striking was the result that in presence of PVCH at concentrations lower than 30 ppm, it was possible to crystallize iPP in the stable monoclinic form in the complete range of processing relevant cooling rates.