Recent analyses suggest that pain is on the rise among working age adults in the US. Like many public health challenges, the burden of pain is unequal. This column explores why knee pain – the top joint problem in the US – differs by education. It finds that physical demands on the job and obesity each explain about one-third of the education gradient in knee pain and that there is an interaction between the two, with physical requirements on the job associated with knee pain primarily in those who are obese.