Walter J. Leonard, the chief architect of an admissions process at Harvard that has been emulated across the United States, opening colleges and universities to more women and minorities, died on Dec. 8 in Kensington, Md. He was 86.

The cause was complications of Alzheimer’s disease, his wife, Betty, said.

The affirmative action formula that Dr. Leonard designed for Harvard allowed recruiters to take into account race and ethnicity, on a case-by-case basis, as one of many factors to consider as they sought to assemble a diverse student body.

Martha L. Minow, the Harvard Law School dean, said the plan “had a ripple effect across the nation” as other institutions, facing demands for greater diversity, adopted similar ones of their own.

The Harvard formula has passed four decades of constitutional muster, though the United States Supreme Court, in its current term, is revisiting rulings on similar policies in a case involving the University of Texas.