With another new season of Mad Men fast approaching, the changing nature of advertising, and along with it the role of ad agencies in the creation of ads, is once again in the spotlight. Digital disruption has clearly been one of the major catalysts for this change, but less has been said about how the transformation is a prime example of open innovation, a focus of my research for many years. This topic has been at the forefront of my mind because, this week, ninety leaders from all over the world have come to HBS to take part in our Leading Change and Organizational Renewal executive education program. What it takes to make the successful shift to open innovation is always an important theme in our discussions. The transformation of advertising reflects this shift in several important ways: