The number of students from the United States who study abroad as part of their curriculum and the number of study abroad programs for students have been steadily increasing over the past 50 years. A review of literature in this area shows that little significant research addressed the effects of studying abroad upon students'' openness to diversity. Further, most studies that have purported to measure study abroad outcomes have failed to use scientifically rigorous methods. This dissertation reports a quantitative study to determine what specific developmental outcome—in terms of openness to diversity—results from students at The Pennsylvania State University participating in an international education program or study outside the United States. The researcher compares measured results with those from a comparison group of students who remained in the United States.