In this article, the authors present a data collection system to provide information about assault-related injuries within Newark, New Jersey. In 2001, Emergency Department (ED) staff at the six hospitals providing emergency medical care within the city collected data on all assault-related ED visits. Individual-level (n = 1,204) and neighborhood-level (n = 262) analyses were conducted; the latter used data from the 2000 U.S. Census. A hotspots map was also generated. At the individual level, one in three ED patients was assaulted by an intimate partner or other family member. In addition, African American males were disproportionately likely to be treated for assault-related injuries. At the socio-structural level, as hypothesized based on Social Disorganization Theory, hierarchical regression analyses reveal that poorer neighborhoods with more vacant housing units have significantly higher rates of assault-related injuries. (Contains 4 tables, 2 figures, and 3 notes.)