This book discusses the role of American police chiefs in contemporary urban settings, using institutional theory as a framework for analysis. From this perspective, the authors review long-term tendencies toward the rationalist modernization of American police agencies. Ongoing `professionalization', unionization and bureaucratization of police work are major themes in the transformations occurring in the modern role of a police chief. The internal and external conflicts and power struggles of police organization are highlighted and the authors argue that the fundamental definition of police work is the root of this conflict. It is necessary for policing paradigms to move away from rule-based, law-enforcement models towards service alternatives that emphasize the situational imperatives and discretionary essence of police work.