This study investigates the relationship between neighborhood transition and criminalization in Washington, D.C. census tracts. The main hypothesis predicts that racially diversified census tracts will experience increases in formal social control (a.k.a. criminalization) of minority and low-income groups due to social tension between race groups. Existing ethnographic literature links neighborhood levels of racial diversity to various forms of criminalization but quantitative literature on the topic is sparse. This study uses demographic census data and official stop-and-frisk data to examine how changes in neighborhood racial composition affect police stop-and-frisk practices in Washington, D.C. The longitudinal nature of the data and the spatial methods employed build upon the existing body of quantitative criminalization research. Findings indicate that increases in racial diversity are associated with increases in the criminalization of black individuals, particularly in tracts that were predominantly black at the beginning of the study period.