In 1961, after earning her undergraduate degree in mathematics from the University of California at Berkeley, Barbara Liskov (then Barbara Huberman) decided to apply to graduate school at Princeton.

The school replied with a form letter explaining that it didn't accept female students. "I was just astounded when I got that," says Liskov. "A little postcard." In retrospect, she says, "I was very naïve."

Though other women at the time might have known they weren't welcome to knock on certain doors, Liskov never spent much time worrying about what she was or wasn't allowed to do. The result has been a remarkable career. In 1968, Liskov, who is now an Institute Professor in the Department of Electrical Engineering and Computer Science and head of CSAIL's Programming Methodology Group, became the first woman--indeed, one of the first people--in the United States to get a PhD from a computer science department. Her research has led to major breakthroughs in such fundamental areas as operating systems, distributed systems, programming languages, and programming methodology. Her ideas helped form the foundation for modern programming languages such as Java, which are designed to make use of self-contained modules of data and instructions that can be developed once and reused to many different ends. Her work on how to keep distributed systems reliable laid the groundwork for achievements like Google's world-spanning architecture of cheap, off-the-shelf servers. Last summer, her achievements were recognized with the Turing Award from the Association for Computing Machinery--an honor that has been called the "Nobel Prize of computing."

"It's hard to imagine what today's programming and distributed systems would be like without Barbara's many seminal contributions," John Guttag, a professor of computer science and engineering who has known Liskov for more than three decades, wrote in a 2008 letter supporting her promotion to Institute Professor. Guttag, who also nominated Liskov for the Turing Award, notes that dozens of prominent computer scientists from whom he solicited support for that nomination were "consistent in that they all said that the work was great" but "inconsistent as to which piece of her work they would choose to say was great." And that, he says, is a testament to the breadth and impact of Liskov's career.

Liskov, a trim, curly-haired woman who wears whimsical socks, doesn't dwell on her accomplishments or honors (she also won the Institute of Electrical and Electronics Engineers' John von Neumann Medal in 2004). Nor does she dwell on the obstacles she had to overcome to make her way in a largely male-dominated field.

"Growing up, I had no idea how important her achievements were," says her son, Moses Liskov, SM '01, PhD '04, who is now an assistant professor of computer science at the College of William and Mary. She was always reticent about her own triumphs, he adds, but would talk with pride about her students, celebrating when they got good jobs or were granted tenure.