 During 1987, Nightingale published his first book, "Earl Nightingale’s Greatest Discovery".Nightingale’s radio program, "Our Changing World", became the most syndicated radio program ever, and was broadcast across the USA, Canada, Mexico, Australia, New Zealand, Fiji, South Africa, the Bahamas, and 23 additional overseas countries, as well as the Armed Forces Network.After his retirement, Nightingale and his wife, Diana, formed the company Keys Publishing.