This paper analyses the polymer crystallization kinetics (obtained via differential scanning calorimetry) for a model eutectic-forming polymer-diluent system, isotactic polypropylene (iPP)-hexamethylbenzene (HMB). The Avrami and Hoffman-Lauritzen crystallization theories were applied to iPP crystallization in the presence of HMB. In addition, an experimental-computational method of obtaining the phase diagram for an eutectic-forming system is presented along with a technique for determining the sequence of phase separation events.