Catherine Fenselau grew up in York, Nebraska. Always interested in science, first archaeology and ultimately chemistry, she attended Bryn Mawr College. The chairman of the chemistry department, Ernst Berliner, became the first of her three mentors. Fenselau received her PhD in organic chemistry from Stanford University, working in the lab of Carl Djerassi, who became her second mentor. For her postdoc at Berkeley, she entered Calvin Melvin's lab, working directly with Alma Burlingame, then at Johns Hopkins University she worked on a broad range of biomedical problems, and her research shifted its direction more toward biochemistry. Her third mentor, Paul Talalay, helped her buy her first spectrometer, which she used for bacterial analysis and for research into anti-cancer treatments. Fenselau accepted the chairmanship of the chemistry department at University of Maryland, Baltimore County, where she established a regional mass spectrometry center. She began analyzing whole proteins, publishing papers about using mass spectrometry to map protein topography and about HIV Gag proteins. Fenselau moved to University of Maryland, College Park, for a two-year stint as chairman of the chemistry department. She was involved in the study of anthrax-Amerithrax-promoting the rapid detection and characterization of bacteria with mass spectrometry and she established the US Human Proteomics Organization (USHUPO), becoming its first president. She continues to teach and to conduct research in proteomics and bioinformatics.