Foreign-born workers in the United States represent a growing share of the science, technology, engineering and math (STEM) workforce in all occupational categories. This fact sheet from the American Immigration Council analyzes data from the American Community Survey to give an overview of the occupational, gender, educational and geographic distribution of foreign-born STEM workers in the United States. It offers a side-by-side comparison of two sets of STEM occupations based on two different STEM definitions. The total number of STEM workers in the U.S. has nearly doubled since 1990, with one-fifth to one-quarter of the STEM workforce being foreign-born in 2015. Foreign-born STEM workers have made significant contributions to innovation and productivity, e.g. 25 percent of high-tech companies founded between 1995 and 2005 had at least one immigrant founder. The foreign-born also dominate among those with advanced degrees -- immigrants make up the majority of STEM workers with doctoral degrees. With STEM occupations projected to grow 13 percent to more than nine million between 2012 and 2022, the U.S. will need about one million more STEM professionals than it will produce over the next decade. The authors suggest that, though increasing U.S.-born STEM workers is essential, foreign-born STEM workers, who tend to be slightly younger than the overall STEM workforce, may still be required in the U.S. to meet future labor needs.