Ten years ago the US Congress authorized the creation of the Strategic Petroleum Reserve (SPR) with the intent of bolstering energy security. Today the Reserve stands at over 450 million barrels of oil-a large and potentially powerful policy instrument. The questions surrounding the Reserve, however, are many, complex, and largely unresolved. This paper examines these questions, in the process reviewing the analytical approaches to resolving them. The Problems of Oil Supply Disruptions Supply shocks are a recurrent feature of the modern, petroleum-fueled economy. Six times since World War II the world has witnessed disruptions in the flow of crude oil from the Middle East. In 1953, 1957, and 1967, taking advantage of excess production capacity, governments and oil companies cooperated to patch the system together (1, 2).