Objective: The aim of this study was to conduct a preliminary evaluation of the hypothesis that fluid intelligence in older adults is associated with the ability to benefit from cognitive-behavioural therapy (CBT), but unrelated to the ability to benefit from non-directive supportive counselling (SC). Method: A sample of 32 older adults who had completed a randomized controlled trial course of either CBT (N = 16) or SC (N = 16) for anxiety disorders took part in the study. The Raven's Coloured Progressive Matrices (RCPM) test was used to assess fluid intelligence. The Beck Anxiety Inventory change scores between pre-treatment and post-treatment were used as an index of ability to benefit from therapy. A measure of depressive symptomatology was also administered to control statistically for the effects of depression on intellectual functioning. Results: The results for the SC group showed a significant and positive association between fluid intelligence scores and anxiety change scores, such that older adults with higher levels of fluid intelligence demonstrated the most benefit from this intervention. In contrast, there was no significant association between level of fluid intelligence and ability to benefit from therapy in the CBT group. Conclusion: CBT for anxiety disorders is suitable for older adults, irrespective of their fluid intelligence, while the nature of SC may render it more sensitive to level of fluid intelligence.