As a service to the field, the ISSCR develops guidelines that address the international diversity of cultural, political, legal, and ethical issues associated with stem cell research and its translation to medicine. The guidelines maintain and underscore widely shared principles in science that call for rigor, oversight, and transparency in all areas of practice. Adherence to these principles provides assurance that stem cell research is conducted with scientific and ethical integrity and that new therapies are evidence-based. Responding to advances in science, the guidelines were updated in 2021 to encompass a broader and more expansive scope of research and clinical endeavor while maintaining the fundamental principles of the research and application. The 2021 guidelines include new recommendations to address the recent scientific advances involving embryos, stem cell-based embryo models, chimeras, organoids, and genome editing.