The so-called pluralization of policing is gathering momentum, and new models are required that take into account the blurring of what have been conventionally considered parallel policing systems, with private security the lesser or junior entity compared to public police. The authors introduce several Australian examples of the relationships between public police and private security and develop a set of descriptive models to account for and explain the main types of existing and emerging relationships. A prescriptive model is then presented to support the view that caution should temper any movement toward totally symbiotic cooperation between public and private policing sectors. The authors conclude the best relationship for the future may be one that maintains a basic separation of powers, with some operational cooperation only where it is deemed essential and where oversight can be provided by executive-level standing committees. 84 references