I always thought that senior executives led most effectively by managing vertically. That is, they spent the majority of their time working upward with their Board of Directors and downward with direct reports. But then the world, in Thomas Friedman’s words, “flattened out.” Markets became more interconnected, global competition grew, demographics shifted and communication tools improved. Boundaries that impeded good results in the old world posed even bigger problems in a world complicated by differences in culture, geography, function, and varied stakeholder concerns. Like you, I witnessed these changes with eyes wide open, but also wondered if the tight grip on leading vertically — via the traditional tools of hierarchy, power, and authority — would still be the chosen path for senior executives.