Since the First International Summit on Human Genome Editing was held in 2015 in Washington, D.C., research on human genome editing has continued to advance rapidly. However, many questions remain about the science, application, ethics, and governance of human genome editing. Of particular concern is the possibility of heritable genome editing, which would alter the human germline, and applications for purposes other than to treat disease or disability. The Second International Summit on Human Genome Editing was convened to advance the global dialogue on these issues.