Background: Extreme appraisals of internal states correlate with and prospectively predict mood symptoms in adults, and discriminate individuals with bipolar disorder from individuals with unipolar depression and non-clinical controls. Aims: These findings required replication in adolescents. This study sought to investigate the relationships between appraisals of internal states, mood symptoms and risk for bipolar disorder in an adolescent sample. Method: A non-clinical sample (n = 98) of adolescents completed measures of mood symptoms, appraisals, and mania risk, alongside covariates. Results: Appraisals of internal states were associated with analogue bipolar symptoms, independently of impulsivity and responses to positive affect. Positive appraisals of activated mood states were uniquely associated with hypomania, whilst negative appraisals were uniquely associated with depression and irritability symptoms. Individuals who appraised activated states as both extremely positive and extremely negative were more likely to score at high or moderate risk for future mania. Conclusions: This study is the first to demonstrate associations between appraisals of internal states, analogue mood symptoms and mania risk in adolescents. Clinical implications are discussed.