Background <p>Predictors and moderators of treatment response to cognitive behavioural therapy (CBT) in older adults with anxiety and/or mood disorders are relatively unknown. Previous studies had small sample sizes and not included social factors, non-social activities, and frequency of negative automatic thoughts (NATs).</p> Method <p>Pooled data from 220 participants aged 60–88 years (<i>M</i> = 67.79, <i>SD</i> = 5.87) who received CBT or a Control in three clinical trials. Participants completed demographic questionnaires, diagnostic assessments, and self-report symptom measures pre- and post-treatment, with a subsample completing 6-month follow-up. Demographic, clinical, and process characteristics were examined for prediction and moderation of treatment outcomes across diagnostic severity, comorbidity, and symptom severity. </p> Results <p>Few demographic characteristics predicted treatment outcomes. Greater severity of disorders and comorbidity were associated with greater symptom reduction across most measures, particularly for CBT. Social anxiety disorder was associated with greater symptom reduction. Fewer pre-treatment NATs predicted greater symptom reduction in Control but were otherwise linked to symptom change over time. More frequent social activities predicted greater symptom change in both conditions, with more frequent non-social activities also predicting greater symptom change in CBT. Social activity moderated treatment effects such that those with more social activities yielded more benefit from Control, whilst social activity did not influence the CBT outcomes. No other variables moderated treatment effects.</p> Conclusions <p>Predictors of CBT response included disorder severity, comorbidity, frequency of NATs, social and non-social activities. Social activities moderate treatment effects. These findings provide new predictors and moderators of CBT response in older adults.</p>