The apprehension productivity of police in a sample of large U.S. cities was analyzed to determine the variations in apprehension rate between cities and within cities, over time, using Part I arrests per sworn officer as an indicator of arrest productivity. It was found that wide variations exist, both between and within cities over time, when arrest productivity is measured by that ratio. When ... [Show full abstract] comparing cities, the range in that measure went from a high of 12.06 to a low of 2.18. Changes within cities over the time period 1968 through 1973 varied from as much as a 47.7 percent increase to a 39.4 percent decrease. An analysis was performed to determine whether crime workload (reported Part I crimes) or police resources (sworn officers) had the greater influence on the generation of arrests. Because of multicollinearity between the variables, it was not possible to conclude which had the greater influence.