One of the biggest decisions companies need to make is whether they want to build in a closed, proprietary ecosystem or an open one. While this is often thought of as a problem for digital companies, it applies to electric car makers, coffee makers, and more. When deciding, companies should follow four principles: 1) embrace the idea that open vs. closed is a spectrum, not a binary, 2) balance benefits and costs through centralized governance, 3) pursue strategic differentiation through different levels of openness, and 4) help educate regulators on the tradeoffs.