In 1994, Steven Messner and Richard Rosenfeld introduced a variation of Merton’s 1938 anomie theory, institutional anomie theory (IAT). Merton argued that the source of crime is found in the ways that society is organized. The IAT version of this theory turns to other aspects of society, such as noneconomic familial, educational, and political institutions to produce a more complete explanation for serious crime. This paper seeks to extend the growing body of research on IAT in several ways. First, it argues that prior tests of the theory have underestimated its potential for explaining macrolevel variation in crime rates by restricting their focus to states and nations. Second, it extends the work of prior research by focusing on the links between institutional anomie and violence using homicides disaggregated according to apparent motivation of the offender. Third, it expands the range of measures of noneconomic institutions considered in prior research. Lastly, it presents conceptual reasons for expecting that noneconomic institutions will primarily mediate the effects of the economy on instrumental violence. In the studies reviewed it was agreed that IAT is a viable and testable theory of serious crime. A goal of this paper was to test the applicability of IAT in explaining homicide by type. The paper focused exclusively on urban counties due to the large bulk of all homicide occurring in urban areas and most previous research focused on urban areas. The majority of measures of noneconomic institutions performed well in explaining variation in all three rates (urban total, instrumental, and expressive) of homicide, the exception being the measure of educational expenditures. It is concluded that noneconomic institutions appear to play an important role in buffering the effects of economic motivation on instrumental violence. Overall, the results support IAT with some limitations. IAT is a viable theory for explaining homicide rates across macrosocial units within the United States and may in fact be well suited for integration with other macrolevel theories. References