Business ecosystems are becoming all the rage. In my recent HBR article, I argued that to embark on shaping an ecosystem strategy, leaders should tackle key questions, including: How can you help other firms create value? What role should you play—orchestrator, partner, participant? How can your organization adapt? Yet these questions only get you to the starting line. To execute an ecosystem strategy, you must also understand how to make an ecosystem work—in particular, this means not only offering a seamless value proposition but also doing the hard work of brokering attractive partnership arrangements and ensuring value capture. These two seemingly opposed, yet interlinked forces form the Yin and Yang of ecosystem success.