Each year, approximately one of every 20 full-time-equivalent workers in the United States gets injured while at work. This statistic highlights the need for an efficient yet adequate and equitable disability insurance (workers' compensation) system to help those workers during their recoveries. Much has been learned about how to balance the priorities for this type of social insurance, but gaps in our knowledge remain. This book presents a set of essays from a group of leading scholars that provide a detailed overview of what is known about the disability insurance system while highlighting areas of the system that beg for greater understanding.