Objective: Adolescence frequently coincides with the onset of psychiatric illness and depression is commonly observed in adolescents. Recent data suggest a role for diet quality in adult depression. Given the importance of adequate nutrition for brain development, it is of interest to examine whether diet quality is also related to depression in adolescents. Methods: The study examined 7114 adolescents, aged 1014 years, who participated in the Australian Healthy Neighbourhoods Study. Healthy and unhealthy diet quality scores were derived from a dietary questionnaire. The Short Mood and Feelings Questionnaire for adolescents measured depression. Adjustments were made for age, gender, socioeconomic status, parental education, parental work status, family conflict, poor family management, dieting behaviours, body mass index, physical activity, and smoking. Results: Compared to the lowest category of the healthy diet score, the adjusted odds ratios (95% confidence interval) for symptomatic depression across categories (C) was: C2 0.61 (0.450.84); C3 0.58 (0.430.79); C4 0.47 (0.350.64); and C5 0.55 (0.400.77). Compared to the lowest quintile, the adjusted odds ratios (95% confidence interval) for symptomatic depression across increasing quintiles of the unhealthy diet score were: Q2 1.03 (0.871.22); Q3 1.22 (1.031.44); Q4 1.29 (1.121.50); and Q5 1.79 (1.522.11). Conclusions: Our results demonstrate an association between diet quality and adolescent depression that exists over and above the influence of socioeconomic, family, and other potential confounding factors.