The position of the Chief of Staff (CoS) to the Australian prime minister has an almost 40-year history, yet little is known about the nature of the job. There is no job description for the prime minister's CoS. Each prime minister has his own agenda. This chapter sketches the theoretical approach and methods and offers illustrative portraits of CoSs since 1972, identifying their several differing conceptions of job. It then discusses the common ground between these several understandings of the job. The chapter explores why the beliefs and practices of the job vary, and discusses personalities of the individuals, events, the skills of the CoS, and expectations of the role. It highlights that the skills and organisational resources of the CoS and prime minister's office are necessary but not sufficient for coping with 'blasts of wild treachery and weirdness' that affect all prime ministers at some point.