A diet-patterns approach has often been used to describe eating patterns in adults but has rarely been used in adolescents. We used principal components factor analysis to: 1) describe the dietary patterns of a cohort of ethnically diverse youth during early and middle adolescence; 2) examine if the patterns persisted 5 y later; and 3) study secular trends. Project EAT-I (Time 1) collected data on 4746 middle school (younger cohort) and high school (older cohort) students in 31 Minnesota schools in 1998-1999. Project EAT-II (Time 2) resurveyed 53% (n = 2516) of the original cohort in 2003-2004. Dietary intake was assessed at Time 1 and 2 using the Youth/Adolescent FFQ. We identified dietary patterns separately by cohort (older/younger) and gender (boys/girls). At Time 1, we identified 4 patterns in early and middle adolescents that were relatively consistent between boys and girls that we labeled vegetable, fruit, sweet/salty snack food, and starchy food. Longitudinal analyses indicated that patterns were relatively stable over 5 y, with the exception of a new fast food pattern. Examination of age-matched secular trends in middle adolescents (older cohort at Time 1, younger cohort at Time 2) showed similar patterns, with the exception of the fast food pattern that emerged at Time 2 among middle adolescent boys. We identified dietary patterns in this adolescent population that differed from those usually found in adults. Patterns were similar across gender and age cohorts and were relatively similar over time, with the exception a new fast food pattern.