Background: There is a considerable body of evidence to suggest that behavioural activation for depression is an equally effective but less complex treatment than cognitive behavioural therapy. It may therefore be more suitable for those who are cognitively impaired (i.e. early-stage dementia or mild cognitive impairment) or have a learning disability. Materials and Methods: A case study is presented that outlines how a behavioural approach was used to support an older adult with a learning disability and mild cognitive impairment who was depressed. It was delivered by the carer liaison practitioner employed by a memory service. Results: The client's score on the GDS-LD reduced from 23 to 5 and on the GAS-ID from 19 to 11 indicating a clinically significant improvement in his symptoms of depression and anxiety at post-treatment. Mood ratings on the Ottawa Mood Scales rose from 2/10 to 7/10. Increased engagement in activities and an improvement in the client's problem-solving abilities were evident. Conclusions: The case study demonstrates the clinical utility of behavioural activation as a treatment for depression in an older adult with a learning disability and mild cognitive impairment. This matches the findings of other studies of behavioural activation as an intervention to treat depression in older adults. However, the client did not have a formal diagnosis of learning disability and may therefore be atypical. More comprehensive studies, including randomised controlled trials, are needed to confirm these findings and more thoroughly test the effectiveness of behavioural interventions with this client group.