Project Summary This application is to request funds to provide partial support for the 9th International Symposium on the Biology of Vertebrate Sex Determination in April of 2023. This symposium has been held at 3-year intervals since its inception in 1997. Due to the pandemic, the originally scheduled symposium in 2021 was postponed to 2023. This unique symposium is attended by the entire international field working on sex determination in diverse vertebrate systems, such as amphibians, fishes, birds, reptiles, monotreme, marsupial, and eutherian mammals, including domesticated species, mice, and humans. It is nearly impossible to keep up with the advances made in so many diverse vertebrate systems. Therefore, the objective of this symposium is to bring the community together so that junior and senior scientists can exchange information, using a comparative approach to advance our understanding of the process of sex determination, sex differentiation, disorders and differences of sex development, and environmental impacts on this process. The first eight symposia yielded many collaborations: reagents were exchanged, experiments planned, and new ways of investigating sex determination discussed. The last symposium in 2018 attracted many junior scientists (~70% of the participants), including graduate students, postdoctoral fellows, and assistant professors. We propose to continue and enhance this tradition by including trainees and junior faculty on the organization committee and empowering them to organize activities beneficial to their careers. We also emphasize on enhancing diversity and creating a harassment-free conference environment. We expect the 9th Symposium to be as productive and stimulating as the previousones and will bring the scientific community together after a 5-year hiatus.