This report examines the differences in self-reported academic performance (i.e., average grades in the last semester or grading period) among students aged 12 to 17 by gender, age, and substance use. All findings are annual averages based on combined 2002, 2003, and 2004 NSDUH data. Researchers found that the frequency of the use of alcohol and marijuana during the past month was related to academic performance. Of students reporting an A or B average: (1) 72.2% were students who did not use marijuana in the past month as compared with 58% of those who used marijuana on 1 to 4 days in the past month and 44.9% of those who used marijuana on 5 or more days during the past month; and (2) 72.5% were students who did not use alcohol during the past month as compared with 67.1% of those who used (but did not binge on) alcohol in the past month and 57.7% of those who engaged in past month binge alcohol use. (Contains 5 endnotes and 4 figures.) (Contains 4 figures.)