Background: Patients with psoriasis are at an increased risk for depression. However, the impact of treatment on this risk is unclear. Objective: Evaluate the incidence and impact of treatment on depression among patients with moderate-to-severe psoriasis. Methods: We defined a study population within the Psoriasis Longitudinal Assessment and Registry and measured the incidence of depressive symptoms (Hospital Anxiety and Depression Scale-Depression score ≥8) and adverse events (AEs) of depression within cohorts receiving biologics, conventional systemic therapies, or phototherapy. Patients were evaluated at approximately 6-month intervals. Multivariate modeling determined the impact of treatment on risk. Results: The incidence rates of depressive symptoms were 3.01 per 100 patient-years (PYs) (95% confidence interval [CI], 2.73-3.32), 5.85 per 100 PYs (95% CI, 4.29-7.97), and 5.70 per 100 PYs (95% CI, 4.58-7.10) for biologics, phototherapy, and conventional therapy, respectively. Compared with conventional therapy, biologics reduced the risk for depressive symptoms (hazard ratio, 0.76; 95% CI, 0.59-0.98), whereas phototherapy did not (hazard ratio, 1.05; 95% CI, 0.71-1.54). The incidence rates for AEs of depression were 0.21 per 100 PYs (95% CI, 0.15-0.31) for biologics, 0.55 per 100 PYs (95% CI, 0.21-1.47) for phototherapy, and 0.14 per 100 PYs (95% CI, 0.03-0.55) for conventional therapy; the fact that there were too few events (37 AEs) precluded modeling. Limitations: Incomplete capture of depression and confounders in the patients on registry. Conclusion: Compared with conventional therapy, biologics appear to be associated with a lower incidence of depressive symptoms among patients with psoriasis.