How to successfully transform a business? I've been intrigued by many stories of breakthrough change in organizations. Take for example Microsoft's creation of the Xbox in 2000. How was it possible that a giant like Microsoft, totally focused on software, with a strong hold on business clients and productivity applications, decided to dive into a journey made of hardware, young consumers, and entertainment? How did it happen that Microsoft developed a totally new platform, the Xbox, with an operative system that was incompatible with Windows, its incumbent core technology? In my studies with Naiara Altuna at Politecnico di Milano and with Rami Shani at California Polytechnic University, have discovered that the story of the Xbox resembles the typical dynamics of breakthrough movements in art and science, such as the impressionism or Viennese school of psychology: the key role is played by a small circle of radical thinkers, i.e. a Radical Circle. This is a small group of peers, not formally related in the organization, but who are directly exposed to changes in the context and therefore start to feel a malaise with the current business direction. Rather than proposing a new radical vision to their top executives (their pitch would hardly succeed since their radical vision would be hardly recognized and supported), these radicals start to work autonomously (often secretly) for a while. Once they emerge, their vision is so robust and powerful to stand the harsher opponents, and it is more easily grasped by others. This article illustrates how a Radical Circle works, and how you can create your own.