Although the high-reliability organization (HRO) literature identifies several attributes that differentiate HROs from other types of organizations, these studies do not explain how an HRO comes into being, nor do they provide a means to gauge or measure the extent to which an organization exhibits the specified features. This article reports the results of a 97-year longitudinal case study tracking the emergence and continuation of HRO characteristics in the Federal Aviation Administration’s air traffic control operations to answer the following questions: how do HRO functions emerge in public organizations, and do policy changes lead administrative changes, or is there little relation between policy and organizational change? The analysis shows that (1) HRO characteristics emerged incrementally over an extremely long period of time, and (2) policy changes preceded organizational changes early in the process of HRO development, but the relationship of policy change to organizational change decreased in later stages.