The political theorist Danielle Allen has won this year’s John W. Kluge Prize for Achievement in the Study of Humanity, a $500,000 award administered by the Library of Congress that recognizes work in disciplines not covered by the Nobel Prizes.

Dr. Allen, a professor at Harvard University and the author of “Our Declaration,” a study of the Declaration of Independence, is known for work that ranges from close readings of historical texts to broad efforts like the Democratic Knowledge Project, a K-12 educational platform aimed at developing skills needed for civic engagement.

At the library, she will lead an initiative called “Our Common Purpose,” aimed at engaging educators, the general public and political leaders in promoting what she calls “civic strength.”

In a statement, Carla Hayden, the librarian of Congress, said the choice of Dr. Allen would further a “timely national conversation” on how to strengthen American democracy.

“Now is an important moment to discuss ways we can all promote civic strength and engagement, which is at the core of our national culture,” Dr. Hayden said.

The Kluge Prize, established in 2003 and given roughly every two years, has long been part of a rarefied group of international humanities prizes that come with a headline-making $1 million award. Past winners, usually older scholars honored for lifetime achievement, have included the philosophers Jurgen Habermas and Paul Ricoeur and the historians John Hope Franklin and Drew Gilpin Faust.