Boards that work well have a constructive critical dialogue among Board members and senior management. This open dialogue is a prime determinant and indicator of Board effectiveness. A CEO needs a strong well-functioning Board to serve as a sounding board, a source of advice and a confirmation of his or her own judgments about how to move forward. This paper argues that Boards of Executive and non Executive Directors in the UK and Advisory and Audit Boards in the US contribute to competitive advantage through open dialogue – amongst Directors as well as between Directors and the management team. Copyright © Charles Smith, PhD.