Examined the validity of the tripartite model of anxiety and depression and its internal structure in children. Measures of positive affect/surgency (PA/S) and negative affect/neuroticism (NA/N) and self-report and peer nominations of symptoms of depression and anxiety were completed by 104 children (mean age = 14.9 years, SD = 1.9). Parents completed measures of temperament and anxious and depressive symptoms. Multitrait-multimethod and confirmatory factor analyses (CFA) supported a 3-factor model that included separate Child and Parent NA/N factors and a joint PA/S factor. Child and Parent NA/N were related to symptoms of both depression and anxiety, but neither parent nor peer symptom ratings related to Child NA/N. PA/S was primarily related to symptoms of depression. These results support aspects of the tripartite model in children and suggest caution in the use of multimethod assessment of children's temperament and internalizing symptoms.