The Mathematical Sciences Research Institute (MSRI) is an independent nonprofit research institution and a center for collaborative research. Its events draw thousands of leading scholars from around the world each year, including intensive semesters organized around pairs of specific themes. This grant supports two semester-long programs at MSRI on market and mechanism design and algorithmic fairness. Mechanism design is a field of economics that studies procedures, assignments, and incentives that work other than through markets and prices. The program will advance research on improving the design of real-world transactions such as organ donation and medical student hospital residency matching. Algorithmic fairness, meanwhile, is concerned with understanding and correcting biases in algorithmic decision-making. Recent research has shown that some properties of algorithmic fairness are mathematically incompatible with each other, and the program will investigate what it means for predictive algorithms to be fair in ways that are both well-motivated and computationally feasible. This grant provides support for 3-6 program organizers, 15 senior research professors, 30-35 research members, 8 postdocs and 12 graduate students, for a total of 70 researchers per program, or 140 researchers in total.