Incomplete response in the treatment of late-life depression is a large public health challenge: at least 50% of older people fail to respond adequately to first-line antidepressant pharmacotherapy, even under optimal treatment conditions. Treatment-resistant late-life depression (TRLLD) increases risk for early relapse, undermines adherence to treatment for coexisting medical disorders, amplifies disability and cognitive impairment, imposes greater burden on family caregivers, and increases the risk for early mortality, including suicide. Getting to and sustaining remission is the primary goal of treatment, yet there is a paucity of empirical data on how best to manage TRLLD. A pilot study by our group on aripiprazole augmentation in 24 incomplete responders to sequential SSRI and SRNI pharmacotherapy found that 50% remitted over 12 weeks with the addition of aripiprazole, and that remission was sustained in all participants during 6 months of continuation treatment. In addition to controlled assessment, evidence is needed to support personalized treatment by testing the moderating role of clinical (e.g., comorbid anxiety, medical burden, and executive impairment) and genetic (eg, selected polymorphisms in serotonin, norepinephrine, and dopamine genes) variables, while also controlling for variability in drug exposure. Such studies may advance us toward the goal of personalized treatment in late-life depression.