Negative cognitive styles (habitual approaches to processing information) and neurotic personality traits reported in affective disorders may have important therapeutic implications in both bipolar and unipolar disorder. In particular, negative cognitive styles appear to predict risk of recurrence of affective disorder and poor therapy outcomes for depressed individuals. Previous research has reported relationships between negative cognitive styles and neuroticism, but none has explored the relative contributions of each prospectively in a mixed bipolar and unipolar sample. Therefore, we evaluated the contributions of negative cognitive style and personality (extraversion and neuroticism) in predicting symptoms and functioning in a sample of 199 participants with affective disorder (76 bipolar, 123 unipolar) and 124 participants at 6-month follow-up (55 bipolar, 69 unipolar). Participants completed self-report measures of negative cognitive style, personality, and quality of life, complemented by observer ratings of affective symptoms and global functioning. Negative cognitive style at baseline was predictive of worse global functioning and quality of life ratings at 6 months, but not of affective symptoms (better predicted by extraversion). Examining the bipolar and unipolar groups separately, negative cognitive style was predictive of 6-month outcomes in quality of life and global functioning in the unipolar group only. Personality did not predict symptomatic or functional outcomes at 6 months in this sample. Implications for therapy are considered.