Effective leadership is discussed from the perspective of styles of supervision and factors that influence the selection of style. Transactional analysis is presented as an analytical technique. Of equal importance in contemporary police supervision are legal aspects of supervision which relate to personnel law and employee rights and address issues of sexual harassment, due process in discipline, and performance appraisal. Performance based supervision is presented as a process that involves performance planning, the establishment of evaluation standards, the ongoing evaluation of personnel, troubleshooting, and motivation. An analysis of the trends that led to the current changes in policing covers the period after World War II and the Korean War, particularly the demographic changes in the cities. Future trends in policing organization lead away from a bureaucratic military model and toward a facilitator style of leadership, incorporating privatization, new technology, and more education and training of officers. 112 references and 19 cases