The cost of four years of undergraduate education, including living expenses, now averages nearly $80,000 at public colleges and over $100,000 at many private institutions. Tuition and fees have risen steadily since 1980, fueling concern that college is becoming prohibitively expensive for many families. This Congressional Budget Office (CBO) paper--prepared at the request of the Senate Budget Committee--estimates how much students and families paid in college costs in the 1999-2000 academic year after accounting for all of that aid. Because a primary purpose of financial aid is to level the playing field among students and because the cost of college differs significantly for different types of institutions (for example, two-year public and four-year private schools), CBO breaks down its estimates by family income group and type of college. Several findings from CBO's analysis suggest that governmental and other nonfamily assistance makes up a particularly large share of financial support for students from low-income families. Reconciling Means of Financing with Tuition and Nontuition Expenditures is appended. (Contains 12 tables, 4 figures, and 15 footnotes.)