Studies have shown that psychiatric patients have significantly impaired quality of life (QOL) in comparison to community samples who are not suffering a mental illness. Despite an increase in research in the mental health field, there still remains little consensus as to the merit of using such questionnaires within a mental health population. There is a concern that QOL is redundant with affective state and symptomatology. We investigated the usefulness of the Quality of Life Enjoyment and Satisfaction Questionnaire-short form (QLESQ-SF) in a depressed outpatient sample receiving time-limited, standardized group cognitive-behavioural therapy. QLESQ-SF ratings were examined at admission and 10-week endpoint in an intention-to-treat (N = 212) and completers (N = 164) sample. QLESQ-SF ratings and symptom ratings (Beck Depression Inventory-II; Beck Anxiety Inventory) improved significantly over time. Hierarchical regression analyses revealed that, although affective state and change in symptomatology were significantly correlated with QOL and change in QOL, a large proportion of variance was unexplained. These results are inconsistent with the theory of measurement redundancy. QOL appears to be a useful measure that provides additional treatment outcome information distinct from affective state and symptomatology.