The cost of a bachelor's degree was estimated and compared for different types of institutions. The objective was to develop a single index to show how much each type of institution spends on producing a bachelor's degree graduate, and to use trend data to show how these costs will change over time. The basic concept associated with the cost of a bachelor's degree and the technical problems involved in the estimation are discussed. Of concern are direct costs, which include only instruction expenditures, and full costs, which include both direct costs and allocated costs. To determine how the major characteristics of colleges affect the costs of bachelor's degrees, schools are classified according to their full costs of bachelor's degree: the low-cost group is the lowest 25% of these ranked institutions, while the highest 25% is the high-cost group, and the ones in between (25-75%) are the medium-cost group. Main factors in cost determination include: the composition of students (e.g., part-timers, graduate students); class size; affluence and prestige; and school size. A sensitivity analysis and methodology modifications are included. Appended are rebuttal comments on the cost issue and the analysis by Paul T. Brinkman and Dennis P. Jones, Alan P. Wagner, and Robert Zemsky and an afterword by Chester E. Finn, Jr. (SW)