A longstanding concerns of the U.S. government is how to strengthen the country's science, technology, engineering, and mathematics (STEM) workforce so that it can remain innovative and productive. Success relies on a sufficient supply and quality of STEM students and workers, and also effective policy initiatives to address technology challenges and workforce numbers. An immigration bill was proposed to Congress that would increase the U.S. supply of guestworkers for STEM employers. In this report from the Economic Policy Institute (EPI), Hal Salzman, Daniel Kuehn and B. Lindsay Lowell review and analyze the STEM labor market and workforce, and the supply of high-skill temporary foreign workers, who serve as "guestworkers." The report also addressees three central issues in the ongoing discussion about the need for high-skill guestworkers in the U.S.