The purpose of this study was to examine the impact on undergraduate college admissions decisions at selective U.S. colleges and universities of student enrolment in the Advanced Placement (AP) or International Baccalaureate (IB) programs of international schools. A total of 30 interviews were conducted by the researcher with admissions personnel from selective colleges and universities in the United States. Additionally, two tracer studies were conducted from two similar international schools; one offering the IB Diploma program and the other offering the AP program. The tracer studies focused on AP/IB enrolment and its impact on college admissions success. Results of the study indicate that there is a strong correlation between enrolment in these programs and admission to selective undergraduate institutions (high correlations of r = -0.77 and r = -0.75 were found in both tracer studies). However, this correlation is influenced by specific secondary school leader commitments to these programs. It is not essential for secondary school students to be enrolled in these programs in order to gain admission to the most selective colleges and universities in the United States since AP and IB enrolment explains roughly 58% of the variance in admissions. Other important factors explain 42% of the variance. These factors were not identified in this study. These results have significant implications for both secondary schools, institutions of higher education, the IBO and College Board. The data from the two tracer studies and the interviews with admissions personnel indicate that participation in these programs enhance admissions chances, but admission is possible without such participation. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]