From 1989 to 1990, Wintersteen was director of the National Pesticide Education Program. She became a professor of entomology at
Iowa State University in 1996, and has also served as the director of the Agriculture and Natural Resources program and associate director of the Iowa Agriculture and Home Economics Experiment Station. Wintersteen was appointed the dean of the
College of Agriculture and Life Sciences in 2006, and became the first endowed dean at Iowa State. She was one of four finalists to succeed
Steven Leath as president of Iowa State University, and, in October 2017, was appointed to the position by the
Iowa Board of Regents, becoming the first woman to take office as Iowa State University president. Wintersteen's installation ceremony took place on September 21, 2018. In 2019, Wintersteen's contract as president was extended by the Iowa Board of Regents through 2023. In 2022, her contract was again extended through 2024. On May 16, 2025, she announced plans to retire in January 2026, pending the appointment of the next president. Wintersteen formerly served on the board of trustees of the Farm Foundation and was on the board of directors of the U.S.-Israel Binational Agricultural Research and Development Fund from 2012 to 2017. She also serves on the
Big 12 Conference Board of Directors. ==Personal==