ABSTRACT Improving outcomes for adult depression in primary care is a leading health care priority and antidepressants are a cornerstone of evidence-based treatment. However, patient non-adherence and discontinuation are common. The proposed study examines use of modest financial incentives in conjunction with tailored text message reminders to determine the most effective and cost-effective support for establishing consistent antidepressant medication taking routines to improve clinical outcomes of adult primary care patients with depression. We propose to conduct a 3-arm RCT (N=525, n=175 per arm) to compare with usual care the short-term and extended effectiveness of two adherence support strategies for primary care patients with depression who have been newly prescribed antidepressant medications. We will examine whether personalized daily text messages with and without financial incentives improves antidepressant adherence and depression symptoms. Adherence will be measured with a wireless pill bottle at 6 and 12 weeks and by assessment of electronic health prescription records at 24 and 52 weeks. Depression symptoms will be collected via telephone by a trained assessor at 6 and 12 weeks. Our Specific Aims are to: 1. Determine the relative effectiveness of 1) 12 weeks of personalized daily text reminders without financial incentives (reminders alone), 2) 12 weeks of the text reminders paired with 6 weeks of financial incentives (reminders and incentives), compared with 3) usual care, and with each other (non-inferiority). The primary outcome will be symptom response on the PHQ-9 depression rating scale at 12 weeks. 2. Explore the effectiveness of each study intervention arm compared to usual care and to each other on antidepressant adherence at 6, 12, 24, and 52 weeks, and whether these effects are moderated by baseline financial security and adherence intentions. We also will assess whether the intervention effects in Aim 1 are mediated by antidepressant adherence. 3. Use qualitative inquiry of antidepressant adherent and non-adherent study patients to explore opportunities to maximize the effectiveness of the financial incentives and reminders to increase antidepressant medication adherence. Widespread problems with antidepressant adherence, especially during the early stage of treatment, undermine the primary care treatment of depression. This study will test whether personalized daily text messages grounded in behavioral economics principles alone or combined with financial incentives based on contingency management principles improves depression outcomes. These two interventions are designed to be readily adapted into primary care workflows through an automated patient-facing system to improve clinical outcomes of adult primary care patients with depression.