OBJECTIVES:There is evidence that diet quality is associated with mental health problems in adults and adolescents. Yet the extent to which overall diet quality (not individual nutrients or dietary patterns) may be associated with mental health problems in pre-adolescent children, a common time for first onset of symptoms, remains unclear. This study examined associations between overall diet quality, using a brief measure, and mental health problems during late childhood, in a large community sample. METHODS:Participants were 787 eight and nine-year-old children taking part in the Childhood to Adolescence Transition Study. Parents reported on their child's mental health problems using the Strengths and Difficulties Questionnaire and on their child's diet quality, using a six-item screening tool. RESULTS:Regression analyses were conducted, adjusting for child age, sex, body mass index, and family socioeconomic status. Overall diet quality was significantly associated with children's mental health before (beta = -0.11, 95% CI -0.18 to -0.04, p = 0.004) and after adjustments for age, sex, body mass index and family socioeconomic status (beta = -0.10, 95% CI -0.18 to -0.03, p = 0.007). CONCLUSION:Concordant with previous literature, results indicate that better overall diet quality is related to more positive mental health in pre-adolescent children. Additionally, these results support the utility and efficacy of a brief (six-item) parent-report questionnaire as an indicator of overall diet quality.