Between March 2020 and March 2021, Congress allocated $189.5 billion for a new Elementary and Secondary School Emergency Relief (ESSER) Fund. The arrival of this federal aid was a lifeline for schools attempting to serve students amid the COVID-19 pandemic. This funding was distributed in a very different manner, and with very different rules and requirements, than we see with other forms of federal and state education aid. This report explores the most significant ways in which this funding differed from school districts' standard funding allocations, and what those differences can teach policymakers both about how to evaluate the ESSER investment and about how to structure and manage future school funding distributions. Our conclusions are informed by in-depth interviews with a number of district and state officials involved in administering and using ESSER dollars.