This study focuses on the postsecondary choices of all SAT[R] takers in the high school graduation cohort of 2006, who graduated from 3,172 public high schools in 17 states where the preponderance of college-aspiring students take the SAT, rather than the ACT. The data set analyzed is constructed by merging the College Board's student-level SAT data to college enrollment data from the National Student Clearinghouse (NSC). The NSC, which is composed of 3,300 participating colleges enrolling 96 percent of American college students, allows the authors to document the postsecondary institutions where SAT takers enroll. Public high school demographic characteristics such as urbanicity and total student enrollment come from the National Center for Education Statistics' Common Core of Data (CCD) for the 2005-06 academic year. The authors restrict the sample to include only the high schools with 50 or more SAT takers. Factors that Determine High School Undermatch Rate are appended. (Contains 5 figures, 2 tables and 12 footnotes.)