William D. Danko, Ph.D. is the coauthor of the bestselling book The Millionaire Next Door, which explores wealth in America through extensive research. The book, co-written with Thomas J. Stanley, delves into the surprising secrets of America's wealthy, examining the behaviors and habits of millionaires in the United States. Danko and Stanley's work contrasts those who are "Under Accumulators of Wealth" (UAWs) with "Prodigious Accumulators of Wealth" (PAWs), revealing that millionaires are often found in middle-class and blue-collar neighborhoods rather than affluent or white-collar communities. This insight challenges common perceptions about wealth and status in America.