In 2008 New Mexico changed its graduation requirements for regular education high school students who completed more than their senior year of high school in a New Mexico public school. Students who entered high school in 2009 were the first to have to complete (pass with a D or better) at least one advanced course (a course designated by the New Mexico Public Education Department as an honors or gifted and talented course or designated by the school district as an advanced, Advanced Placement, gifted and talented, honors, or International Baccalaureate course), dual-credit course, or distance learning course. Numerous studies have shown the positive academic outcomes--such as higher high school graduation and postsecondary enrollment and persistence rates--associated with completing advanced courses. This study examines advanced course completion rates (the percentages of students who completed zero, one, and two or more advanced courses) among New Mexico public high school students in the first three cohorts subject to the state's new graduation requirements to identify whether gaps exist in the state and across student and school characteristics. It uses data on students who entered grade 9 in 2009-11 and remained enrolled for four years. The student characteristics examined were race/ethnicity, grade 8 standards-based assessment performance in math, eligibility for the federal school lunch program, and English learner status; the school characteristics examined were performance rating, size, Title I status, and urbanicity. The findings may help New Mexico policymakers and practitioners understand the extent to which traditionally underserved populations complete advanced courses in high school. The study found that over 56 percent of New Mexico students completed at least one advanced course in high school but that gaps exist across racial/ethnic groups. White students were more likely than American Indian students and Hispanic students to complete an advanced course. The gap in the advanced course completion rate between White students and American Indian students was 17 percentage points, and the gap between White students and Hispanic students was 14 percentage points. The gaps across racial/ ethnic groups were smaller when high-performing students (those who received a score of met expectations or exceeded expectations in math on the state's grade 8 standards-based assessment) were examined separately. When high-performing students were examined separately, the gap between White students and American Indian students was 6 percentage points, and the gap between White students and Hispanic students was 4 percentage points. The percentage was much lower among lower performing students (51 percent among lower performing American Indian students, 52 percent among lower performing Hispanic students, and 64 percent among lower performing White students), and substantial gaps remained across racial/ethnic subgroups. The study also found that advanced course completion rates were related to school characteristics. The percentage of students who completed at least one advanced course was higher among students at schools with a performance rating of A on the state's A-F scale than among students at schools with a lower rating. The percentage who completed multiple advanced courses was substantially lower among students at small schools (those with fewer than 750 students) than among students at bigger schools. The gaps remained when high-performing students were examined separately. The percentage who completed at least one advanced course was lower among high-performing students at small schools than among high-performing students at bigger schools. Although this study was not designed to investigate the causes of gaps in advanced course completion rates, identifying the gaps across student and school characteristics is a first step in helping members of the New Mexico Achievement Gap Research Alliance develop strategies to reach traditionally underserved students. The next step could be to investigate areas for improvement in approaches to promoting awareness of the availability and benefits of advanced course completion among American Indian and Hispanic students. The finding that a large share of these students do not complete advanced courses highlights the need to further investigate the extent to which advanced courses are available to students across the state, particularly in small schools and schools with low performance ratings.