This Article evaluates several leading proposals for geoengineering governance with respect to Jasanoff’s “technologies of humility” rubric, which is anchored in four key questions: “What is the purpose; who will be hurt; who benefits; and how can we know?”1 It draws on historical examples (such as the 1978 Environmental Modification Treaty, the 1972 Asilomar conference on recombinant DNA, and the emergence of the International Atomic Energy Agency) to examine the limitations of voluntary codes of conduct and treaties, the most popular approaches to governing geoengineering. Next, the Article examines the relevance of environmental assurance bonds, which would require geoengineers or their funders to post a guarantee price-equivalent to the worst-case threats posited by a particular deployment scheme. Finally, the Article envisions how critically engaging with Jasanoff’s framework could enrich leading approaches to geoengineering governance while diminishing the risk of moral hazard.