On May 21, 2009, Leon Kass delivered the 38th Jefferson Lecture in the Humanities at the Warner Theatre in Washington, D.C.

The Jefferson Lecture was established in 1972 as the highest honor the federal government bestows for distinguished intellectual and public achievement in the humanities.

Past Jefferson Lecturers include John Updike, Harvey Mansfield, Tom Wolfe, Donald Kagan, Helen Vendler, David McCullough, Henry Louis Gates, Jr., Arthur Miller, James McPherson, Caroline Walker Bynum, Bernard Bailyn, Stephen Toulmin, Toni Morrison, Vincent Scully, Gwendolyn Brooks, Bernard Knox, Walker Percy, Cleanth Brooks, Sydney Hook, Barbara Tuchman, Saul Bellow, John Hope Franklin, Robert Penn Warren, Erik Erikson, and Lionel Trilling.