Leaving a high-flying job in consulting, Angela Lee Duckworth took a job teaching math to seventh graders in a New York public school. She quickly realized that IQ wasn’t the only thing separating successful students from those who struggled.

Duckworth found that the most successful freshmen at Penn were students with the highest grit scores. Grit was more important than being at the top of their high school class (as measured by GPA and test scores). She found the same thing with contestants at the National Spelling Bee. Those with the most grit beat those with higher verbal IQ scores. And her test was a great predictor of success at West Point. The cadets with the highest grit score were most likely to finish Beast Barracks, the grueling basic-training course.

HERE, she explains her theory of “grit” as a predictor of success.