Abstract: Food security is becoming one of the most significant political, economic and environmental challenges faced by governments around the world. Despite Australia’s wealth and abundant agricultural resources, this issue affects Australian cities. In order to develop effective strategies to decrease the vulnerability of Australian cities to food supply disturbances, the nature of food flows between cities and the agro-ecosystems upon which they depend must first be understood. Australia’s urban populations tend to be affluent and have specific expectations regarding the types of food they believe should be available to them all year round. The corporations that supply these consumers draw on food sourced from remote agro-ecosystems with little regard for local or seasonal produce. The vulnerability of a city’s food supply therefore no longer depends on local constraints affecting its immediate hinterlands, but on ecological and socio-political factors affecting the remote regions from which its food is sourced. Therefore, urban food security is largely contingent on the specific interrelationships, dependencies and constraints that have developed within the national and international food production system. Through an examination of what is known about food flows in the Australian Capital Region, this paper argues that current ways of understanding and defining food security should be shifted and expanded to account for numerous factors that are presently neglected. This case study provides insights into the food security challenges that Australian cities may face and indicates a number of vulnerabilities associated with the current food supply system. Perhaps most importantly, it demonstrates that a comprehensive assessment of the food security of Australian cities cannot be made until identified data gaps have been filled.