Background: Stress and other mental health issues can negatively impact the health and academic performance of college students. Purpose: Examine relationships among stress, mental health, and academic classification in a national sample of college students. Methods: Analyses utilized secondary data from 27 387 college students responding to the Fall 2009 American College Health Association-National College Health Assessment (ACHA-NCHA) II. Results: In general, undergraduates reported significantly higher rates of feelings and behaviors related to poor mental health and negative effects on academic performance than graduate students. Graduate students and undergraduate students reported significantly different levels of stress. Chi [superscript 2](4) = 54.34, Cramer's "V" = 0.045, "p" = 0.001. Graduate students (74.0%) were also more likely to seek mental health care services in the future than undergraduates (64.8%), Chi [superscript 2](1) = 101.12, Cramer's "V" = 0.061, "p" = 0.001. Translation to Health Education Practice: Stress and mental health differences exist between undergraduate and graduate students. For universities, understanding such differences is critical to the delivery of effective health education programs. (Contains 4 tables.)