Naturally occurring materials like rubber predate the development of science and engineering as we know it today. Historically, rubber and more generally elastomers, known as a class of high polymers, are versatile and useful materials. Rubber is still an elastomer of choice for many engineering applications. After decades of R&D, scientists and engineers realized that technology needs good science. This position is nicely summarized in Figure 1. This scenario brings together four main items that are essential to create and to maintain quality industry(ies). In the case of rubber, particularly natural rubber, it is not only essential to understand these individual properties, but also to comprehend the important interrelationships that contribute to material behavior. In this respect, rubber has been an enabling resource material that has served as a paradigm amongst synthetic polymers in their developmental stages. In this article crystallization of natural rubber especially, is addressed in order to provide some perspective on items that relate to the relevant areas of the pyramid. This overview is far from exhaustive on the crystallization aspects of rubber, but hopefully it strikes a balance between thermodynamics and kinetics, since each discipline has contributed significantly to improve our understanding of polyisoprenes, and in a wider sense to crystallization and morphology that helps determine properties relevant to rubber and to polymers in general.