David J. O'Regan has authored nine books on auditing and related themes. His interests include the application of Aristotelian logic to the auditing process, and he is the author of the Auditor's Companion: Concepts and Terms from A to Z (Georgetown University Press, 2024). He earned a doctorate in accounting and finance from the University of Liverpool and is a Fellow of the Institute of Chartered Accountants in England and Wales. His auditing experience covers more than three decades, spanning the private, public, and academic sectors. He commenced his career in the United Kingdom with Price Waterhouse, a forerunner firm to today's PricewaterhouseCoopers, and subsequently worked in industry before heading the internal audit function at Oxford University Press. He then entered public service in the United Nations system, initially at the Organisation for the Prohibition of Chemical Weapons in The Hague, Netherlands. From 2009 he has served as Auditor General to the Pan American Health Organization in Washington D.C.