This chapter contains sections titled: Nucleation and Growth Heterogeneous Nucleation and Growth Prior to Impingement Avrami Equation for Heterogeneous Nucleation that Accounts for Impingement of Spherulites Crystallization Kinetics and the Avrami Equation for Homogeneous Nucleation of Spherulites Linear Least Squares Analysis of the Kinetics of Crystallization via the Generalized Avrami Equation Half-Time Analysis of Crystallization Isotherms Maximum Rate of Isothermal Crystallization Thermodynamics and Kinetics of Homogeneous Nucleation Temperature Dependence of the Crystallization Rate Constant Optimum Crystallization Temperatures: Comparison Between Theory and Experiment The Energetics of Chain Folding in Semicrystalline Polymer–Polymer Blends that Exhibit Multiple Melting Endotherms Melting Point Depression in Polymer–Polymer and Polymer–Diluent Blends that Contain a High-Molecular-Weight Semicrystalline Component References Problems