Similar studies have led to important discoveries in the past. For instance, the Framingham Heart Study in the United States, which began in 1948 and continues today, led to the discovery in 1960 that cigarette smoking increases the risk of heart disease. In fact, much of what we understand today about the causes of common diseases comes from health studies of the general population. What sets the Ontario Health Study apart from other studies is its potential to reach a large and diverse population residing in Ontario. With it being possible to follow the health of so many diverse people, the Study may detect new risk factors or combinations of risk factors and may be able to investigate many less common diseases. The OHS will also take advantage of the opportunity to link to many valuable sources of information that are unique to Ontario, such as the Ontario Cancer Registry. Some of the best-linked health data in the world – collected for routine administrative purposes – exists in Ontario.