Background: Meta-analyses show efficacy of several psychological and pharmacological interventions for latelife psychiatric disorders, but generalization of effects to routine mental health care for older people remains unknown. Aim of this study is to investigate the improvement of functioning within one year of referral to an outpatient mental health clinic for older adults. Methods: Pre-post measurement of the Health of Nations Outcome Scale 65+ (HoNOS 65+ ) in 704 older people referred for psychiatric problems (no dementia) to any of the seven participating mental health care organizations. Results: The pre-post-test Cohen's d effect size was 1.08 in the total group and 1.23 in depressed patients, the largest subgroup. Linear regression identified better functioning at baseline, comorbid personality disorder, somatic comorbidity and life events during treatment as determinants of a worse outcome. Conclusions: Functioning of older persons with psychiatric problems largely improves after treatment in routine mental health care.