Policymakers have long been concerned about the disparities in college attendance between more and less advantaged groups of students. Upward Bound is one of the largest and longest running federal programs designed to help economically disadvantaged students prepare for, enter and succeed in college. Since December 1991, Mathematica Policy Research, Inc., (MPR) has been conducting the national evaluation of Upward Bound for the U.S. Department of Education (ED). The evaluation has focused on program implementation issues and the effects of the program on student outcomes. The "impact study" is designed to measure the impacts or effects of regular Upward Bound on student outcomes, and it is based on a longitudinal evaluation in which eligible applicants from a nationally representative sample of projects were randomly assigned to Upward Bound or to a control group. The results in this document are based on the national evaluation's third follow-up data collection, which was completed in 2000. Because the entire sample of students was beyond high school age by that time, the report includes updated findings on the effects of Upward Bound on high school outcomes. In addition, based on data covering the first few years after sample members left high school, the report addresses the following research questions: (1) What effect does Upward Bound have on students' postsecondary experiences? (2) Who benefits most from Upward Bound? and (3) What is the association between staying in Upward Bound and student outcomes? Findings in this report suggest that for the average student, Upward Bound: (1) increased the number of high school math credits earned by participants; (2) did not affect other measures of high school academic preparation; (3) may have increased enrollment at four-year institutions; and (4) did not affect enrollment at postsecondary institutions more generally when all types of postsecondary institutions are considered. Appended are: (1) Sample Design Unit Nonresponse and Weights; (2) Baseline Characteristics of the Treatment and Control Groups, Third Follow-Up Survey Respondents; (3) Program Effects and Standard Errors; (4) The Effect of Upward Bound on High School Outcomes by Selected Subgroups; (5) The Effect of Upward Bound on College Engagement by Selected Subgroups; (6) Methods Used to Estimate the Effects of Additional Upward Bound Participation; (7) Weighted Standard Deviations for All Outcome Variables; (8) Data Collection; and (9) Sample Sizes and Standard Errors for Reported Impact Estimates. (Contains 29 tables and 3 figures.)