This pilot study will be a randomized, real-world effectiveness study. Patients diagnosed with major depressive disorder starting a new prescription for an antidepressant monotherapy will be eligible for participation. The study will enroll 40 patients (20 in an observational arm of usual care and 20 with access to a mobile health application). No intervention will occur in the usual care arm. The intervention in this study is a mobile health app, which provides patients with a way to track emotional wellbeing and depression symptoms, set up medication reminders, track adherence to medications, record side effects experienced, and take surveys/tests to assess cognitive symptoms and depression. Patient reported outcomes and clinical data will be collected at baseline and at study primary endpoint (18 weeks) to assess changes over time and between groups for: patient-provider engagement, disease severity, quality of life, employment productivity, cognitive function, resource utilization, and medication adherence. Additionally, resource utilization will be assessed at the one year time point. A Student's t test, if allowed for by the data distribution, will be used to assess between group differences in patient reported outcome scales assessing patient-provider engagement.