This study tested the utility of the theory of planned behavior (TPB) to explain adolescent fast-food consumption among 349 high school adolescents. Subjective norms were further investigated to identify how parents and friends influenced adolescent fast-food consumption. Study participants completed a paper-based questionnaire measuring adolescent attitude, subjective norms for parents and friends, perceived behavioral control, and behavioral intention. Path analysis revealed that TPB explained adolescent fast-food behavioral intention to consume fast food. The model identified parent subjective norms had the strongest relationship with adolescent behavioral intention to consume fast food. Parent norms differed across age and grade in high school. Older adolescents perceived more approval for eating fast food than younger adolescents. Theoretical and practical implications are discussed.