The economic costs and benefits of educating foreign students in U.S. public and private colleges are estimated. U.S. costs of educating foreign students consist primarily of: (1) direct educational costs, (2) cost of the foreign students who receive their maintenance allowance from U.S. sources, (3) travel costs of those foreign students whose travel is financed from U.S. sources, and (4) other administrative costs related to special problems of foreign students. Two problems in estimating foreign student educational costs involve the marginal or the average cost, and adjusting for over-representation of foreign students in relatively expensive courses in science and graduate studies. To calculate the weighted average cost of a foreign student, it is necessary to determine the distribution of foreign students by field and level, and average cost by field and level. Economic benefits to the United States primarily come from tuition payments, unpaid research by graduate students, contributions to aggregate demand, and value of embodied capital in non-returnees. For these different areas, actual cost-benefit calculations are shown. Data were obtained from the National Longitudinal Study of Young Men 14-24 years old in 1966. (SW)