The Main Street Lending Program was the last of the facilities launched by the Fed and Treasury to support the flow of credit during the COVID-19 pandemic of 2020-21. The others primarily targeted Wall Street borrowers; Main Street was for smaller firms that rely more on banks for credit. It was a complicated program that worked by purchasing loans and sharing risk with lenders. Despite its delayed launch, Main Street purchased more debt than any other facility and was accelerating when it closed in January 2021. This post first locates Main Street in the constellation of COVID-19 credit programs, then looks in detail at its design and usage with an eye toward any future programs.