A growing number of educators and policymakers have begun focusing on the goal of preparing all or nearly all high school students for college and other advanced postsecondary learning opportunities. To meet this goal, states are adopting policies to encourage nearly all students, not just those seeking entry into competitive four-year colleges, to take a full core curriculum of college-preparatory courses in high school. Yet it is much easier to give students credit for a course labeled "Algebra II" than it is to ensure that those students actually learn algebra. So how do educators and policymakers know that students are actually learning the content implied by the course titles? This report identifies 10 essential elements of a statewide longitudinal student data system that make addressing questions about course completion, course credit inflation and college readiness possible. They are: (1) A statewide student identifier; (2) Student-level enrollment and demographic data; (3)The ability to match student-level test records across years; (4) Information on untested students; (5) Matching students with their teachers; (6) Student-level transcript (course completion and course grade) information; (7) College readiness test data (SAT and ACT exam results); (8) Student-level graduation and dropout data; (9)The ability to match student records between the P-12 and higher education systems; and (10) A state data audit system assessing data quality, validity and reliability. (Contains 1 table, 1 figure and 10 footnotes.) [This document was produced with the National Center for Educational Achievement.]