Currently, little is still known of spermatid development during spermiogenesis in snakes. There are only two complete ultrastructural studies on ophidians that detail spermatid ultrastructure within two venomous species: The Cottonmouth Snake and the Sea Snake. Therefore, this research was carried out with the goal of broadening our knowledge of the ontogenic steps of spermiogenesis within snakes, particularly in the Colubridae family since no other nonvenomous snake family has been studied. This was accomplished by studying spermatid maturation in the Colubridae snake Masticophis flagellum (Coachwhip snake) using transmission electron microscopy. M. flagellum specimens were gathered in the fall of 2013 in Arkansas, which is the time of year they are highly active spermiogenically. The testes were removed, placed in Trump’s fixative, and tissues were processed for standard electron microscopy. Many of the ultrastructural spermatid details in the Sea Snake are similar to what has been described for squamates and ophidians. The hypothesis for this study was that spermiogenesis in the Coachwhip will have a number of notable differences in spermatid development compared to the two previously studied viperids. Most differences in spermatid development in the viperids studied to date occur in the proximal flagella, condensation pattern of the nuclear chromatin, and the acrosome complex. Other features of the spermatid architecture were similar between what has been observed in the Cottonmouth and Sea Snake. Although the spermatids within snakes appear to be well-conserved, there are differences in intracellular details between previously studied snakes, particularly in the development of the midpiece and principal piece of the flagellum, and in the elongation process of the ii spermatid. The significance of such key character differences during spermiogenesis in snakes is still unknown. Presently, there have not been enough species investigated to elucidate the phylogenetic implications of such fundamental character differences during spermiogenesis, which is the main purpose of such a study in M. flagellum.