This is the third edition of the NSF Science Plan for the Natural Hazards Engineering Research Infrastructure (NHERI). It was developed to focus natural hazards research on some of the major challenges communities face as they work to enhance their resilience to natural hazard events. It provides information for researchers, funding agencies, practitioners, students, and the public on the critical research needs and the process of conducting multi-hazard research to advance hazards engineering practice and community resilience. The Science Plan provides Grand Challenges and Key Research Questions.