Color changes are observed across a wide range of taxa and can provide a variety of functions, such as communication, thermoregulation, and camouflage. One type of color change observed in various species is pattern change, occurring notably during development as ontogenetic pattern change. Ontogenetic pattern change may continue throughout maturation to align with changing morphology and behavior as the organism ages. We studied the ontogenetic pattern change in Gila monsters, because they are easily maintained in captivity, and undergo ontogenetic change. For this thesis, we examined (1) the relative change in the presence and distribution of the two contrasting skin colors over time, as well as (2) the importance of growth vs. age in the timing of pattern change in Gila monsters. Using FIJI and R Studio software to analyze the data/pictures, the data suggested that neonate Gila monsters start with a high standard deviation in their light spots, and experience pattern breakup (increasing their light/dark spot count), whilst maintaining similar proportions of dark/light areas as they develop. We also found that age is the main driver of ontogenetic change in Gila monsters across 60 weeks, not growth.