Background: Few studies have used dietary pattern analysis, a useful method to summarize dietary intake, in adolescents. Objective: Examine sociodemographic and socioenvironmental correlates of habitual dietary patterns. Design: Data for this cross-sectional/prospective analysis were drawn from Project EAT (Eating Among Teens), a population-based study. Subjects/setting: Project EAT-I (Time 1), collected data on 4,746 adolescents in 1998-1999. Project EAT-II (Time 2) resurveyed 53% (n=2,516) of the original cohort 5 years later in 2003-2004. Dietary intake was assessed using the Youth/Adolescent Food Frequency Questionnaire. Main outcome measures/statistical analysis performed: Factor analysis identified four dietary patterns at Time 1 (vegetable, fruit, starchy food, and snack food) and Time 2 (vegetable and fruit, fast food, starchy food, and snack food). Linear regression was used to examine the relationship of Time 1 socioeconomic status and race (mutually adjusted) on factor scores for each dietary pattern, and then of Time 1 socioenvironmental characteristics (adjusted for socioeconomic status and race) on these factor scores. Results: In prospective analyses, socioeconomic status, family meal frequency, and home availability of healthy food were positively associated with the vegetable and fruit and starchy food patterns and inversely associated with the fast food pattern. Home availability of unhealthy food was inversely associated with the vegetable and fruit and starchy food patterns and positively associated with the fast food and snack food patterns. Maternal, paternal, and peer support for healthy eating were positively associated with the vegetable and fruit pattern and inversely associated with the fast food pattern. Similar associations were seen in cross-sectional analyses. Conclusions: Multiple correlates of dietary patterns were identified. Health professionals should target these factors to improve the dietary quality of habitual eating practices in adolescents by encouraging parents to decrease home availability of unhealthy food while increasing availability of healthy food, family meal frequency, and parental support for healthy eating.