The prevalence of Parkinson’s disease and parkinsonism has been on the rise since the 1970’s, but a true estimate of how many people are affected had been difficult to ascertain because of how we collected the early data. It is important to know the prevalence of the disease in order to allocate health care resources, including health care professional training as well as money for research into the conditions of PD. The Parkinson’s Foundation has taken a leading role in determining the prevalence of PD and related conditions in the North American population through the Parkinson’s Prevalence Project. James Beck, vice president for scientific affairs and chief scientific officer of the Parkinson’s Foundation, says he believes the number of people living with Parkinson’s in the United States has been dramatically underestimated and does not represent the ethnic diversity of people affected due to the way in which we gathered older data. He explains how the Parkinson’s Prevalence Project is designed to give a clearer picture of PD in North America.