Depression is one of the most common nonmotor features observed in Parkinson's disease (PD), affecting approximately 40% of patients. Depression in Parkinson's disease (dPD) significantly affects quality of life of both patients and their families and has been shown to be more predictive of distress than motor disability. Depression frequently goes unrecognized in this population, however, in part because the diagnosis is often complicated by the overlap of psychiatric and PD symptoms. The etiology of dPD is unclear; dopaminergic, serotonergic, and noradrenergic systems may be implicated. Options for managing dPD include antidepressant medication; cognitive-behavioral therapy; behavioral lifestyle interventions such as exercise; and, in refractory cases, noninvasive brain stimulation (electroconvulsive therapy, transcranial magnetic stimulation). Randomized controlled trials are needed to evaluate the efficacy of interventional approaches for dPD; several trials are currently underway.