Kleiman, founder of the Electronic Numerical Integrator and Computer (ENIAC) Programmers Project, tells the story of six women who programmed the first general purpose computer. During World War II, the U.S. government recruited mathematicians—mostly women—to faster calculate ballistics trajectories since many men had been drafted in the war. Six of the women had to learn how to use the machine on their own; they pioneered programming techniques and best practices that are still in use today. Kleiman includes short biographies of each of the six women and describes their lives while working on the ENIAC project at the University of Pennsylvania. She details the work that they did and notes introductory programming concepts for unfamiliar readers. Also explored is the sexism the women experienced when the men on the project took credit for their work. Kleiman also chronicles the women’s lives after they left the ENIAC project as well as her own experiences uncovering their stories. VERDICT A compelling account of an underappreciated group of pioneering women.