The Adult-to-Adult Living Donor Liver Transplantation Cohort Study (A2ALL) is a network of nine liver transplantation centers in the United States and Canada. Created by the NIH in 2002, the A2ALL project has been influential in studying the risks and outcomes of living donor liver transplantation. Since its establishment, A2ALL has made major contributions to research on the future medical outcomes and quality of life for living liver donors.