This book provides background and analysis of the premiums charged by the Pension Benefit Guaranty Corporation (PBGC), which is a government-owned corporation that was created in 1974 to protect the retirement income of participants in private-sector, defined benefit (DB) pension plans. When a company terminates a DB pension plan that does not have enough assets to pay 100% of the promised benefits, PBGC pays, in accordance with statute and up to a maximum yearly dollar amount, the benefits to participants in the terminated plan. In FY2012, 887,000 individuals received $5.5 billion in benefit payments from PBGC. An additional 614,000 workers will receive benefits when they retire. PBGC consists of two insurance programs: (1) a multiemployer pension program, which protects the benefits of 10.3 million participants in collectively bargained DB pensions in which several employers make contributions, and (2) a larger single-employer pension program, which protects the benefits of 33.4 million participants in DB pensions operated by one employer for its eligible employees.