Who is the most underemployed of them all? New research taps the youngest and most highly educated members of the workforce.

Some 34% of millennials who hold a PhD report being underemployed, compared to 27% for Generation Xers and 25% of boomers, according to a new report by Millennial Branding, a branding and consulting firm, and PayScale, a company that collects data on salaries. Millennial MDs are underemployed at a rate of 30%, versus 22% of Gen Xers and 21% of boomers. Underemployment can mean they are underpaid for their education and training, not using their education and training in their current job and/or are working part-time, but are still seeking full-time work.