By 1976-77 almost four million teachers and other school personnel belonged to teacher retirement systems or public employee retirement systems. To help laypersons better understand these systems, this report describes the institutional characteristics of public pension funds whose members include teachers and explains the concepts behind such public retirement systems. Data are drawn from U.S. government sources, the National Education Association, and a survey of public pension funds in 49 states and 7 municipalities. The report first describes the number, size, and eligibility criteria of teacher retirement systems. It then discusses the funds' benefits (including income and insurance plans), the "vesting" in employees' names of their rights to their pensions, and the relationships of pensions to other post-retirement income. Following a review of the methods of funding pensions and of calculating each fund's pension obligations, the authors examine the systems' administrative structures and the fiduciary responsibilities of fund administrators. (Author/RW)