The study found that increases in positive affect predicted subsequent reductions in depression and anxiety symptoms, regardless of the type of psychotherapy received. In contrast, symptom improvement did not predict later increases in positive affect, suggesting that positive affect may act as an active mechanism of change rather than simply a consequence of recovery. Decreases in negative affect were also associated with later symptom reductions, particularly in treatments designed to enhance positive affect. Overall, the findings highlight the importance of targeting positive affect alongside negative affect in psychotherapy and suggest that fostering positive emotions may play a key role in improving outcomes for depression and anxiety.