Microsoft's and Wal-Mart's preeminence in modern business has been attributed to any number of factors--from the vision and drive of their founders to the companies' aggressive competitive practices. But the authors maintain that the success realized by these two very different companies is due only partly to the organizations themselves; a bigger factor is the success of the networks of companies with which Microsoft and Wal-Mart do business. Most companies today inhabit ecosystems--loose networks of suppliers, distributors, and outsourcers; makers of related products or services; providers of relevant technology; and other organizations that affect, and are affected by, the creation and delivery of a company's own offering. Despite being increasingly central to modern business, ecosystems are still poorly understood and even more poorly managed. The analogy between business networks and biological ecosystems can aid this understanding by vividly highlighting certain pivotal concepts. The moves that a company makes will, to varying degrees, affect the health of its business network, which in turn will ultimately affect the organization's performance--for ill as well as for good. Because a company, like an individual species in a biological ecosystem, ultimately shares its fate with the network as a whole, smart firms pursue strategies that will benefit everyone. So how can you promote the health and the stability of your own ecosystem, determine your place in it, and develop a strategy to match your role, thereby helping to ensure your company's well-being? It depends on your role--current and potential--within the network. Is your company a niche player, a keystone, or a dominator? The answer to this question may be different for different parts of your business. It may also change as your ecosystem changes. Knowing what to do requires understanding the ecosystem and your organization's role in it.