The research aimed to overcome the limitations of research based on arrest rates, given that victimization data had crucial shortcomings and arrest rates did not measure all crimes or even all crimes known to the police. Social threat interpretations derived from the assertion of conflict theory that law enforcement and police expenditures concentrate on minorities because the of 'the ruling elites’ perceptions of threat and fear of crime. The research tested hypotheses regarding a positive association between percentage black and arrest differentials in cities, independent of criminal conduct, and for arrest differentials in cities with populations that were less than or more than 50 percent black persons. Results indicated a significant relationship between the proportion black and arrest differentials. Findings also suggested that this relationship may be a reflection related more to whites’ perceptions of threat relative to the proportion of black persons in a city’s population than to black persons’ criminal conduct. Tables and 62 references (Author abstract modified)