Social Security Disability Insurance (SSDI) provides benefits to nonelderly workers and their eligible dependents if the worker paid Social Security taxes for a certain number of years and is unable to perform substantial work due to a qualifying impairment. Chapter 1 provides an overview of the DI trust fund and its current financial outlook. Chapter 2 discusses the rules and processes used to determine eligibility for SSDI and SSI. It also explains how benefit amounts are computed, the types of non-cash benefits available to individuals who meet SSA's disability standards, and how each program is financed. Chapter 3 analyzes the relative importance of factors affecting SSDI benefit receipts and terminations over the past 30 years. Chapter 4 examines what is known about how coverage and key features of SSDI and PDI compare, and the potential implications of three distinct proposals to expand employer-sponsored PDI on the Disability Insurance Trust Fund and various stakeholders. Chapter 5 examines trends in SSA's transfers and processing times of appealed cases over the past decade, SSA's monitoring of efforts to meet processing time goals through case transfers, and any challenges SSA faces in transferring cases between offices. Chapter 6 is the statement of Elizabeth Curda on SSA disabilty programs.