This chapter considers the research, development, and implementation of solar geoengineering by nonstate actors and their governance by intellectual property policies. Although some observers are concerned that nonstate actors could deploy it, states will probably retain control over operational decision-making regarding large-scale outdoor tests and implementation. At the same time, commercial entities will play roles – most likely as contractors in public procurement – as providers and innovators of goods and services for solar geoengineering activities. A leading means through which states govern nonstate actors in innovative domains is policies for intellectual property, particularly patents. This chapter reviews the current landscape of patents related to solar geoengineering and the social challenges that such intellectual property could pose. It comments on others’ proposals for intellectual property policies specific to solar geoengineering and also recommends one. Importantly, the suggested "research commons," which is centered on a system of patent pledges, does not require state action and could arise bottom-up among researchers and other nonstate actors.