Poor adherence to treatment is a global problem in depression care, with one-third of patients discontinuing antidepressants in the first month of treatment. Community healthcare workers (CHWs) have successfully used Motivational Interviewing (MI) to improve treatment adherence for various illnesses in the US and globally. However, persistent challenges include: 1) lack of real-time support for communication skills (such as MI) as the CHWs are talking to the patients; and 2) decay of MI skills among CHWs through time in the absence of ongoing supervision because CHWs work away from facilities, traveling from one patient's home to another. Mobile health (mHealth) tools have the potential to address these challenges by: 1) providing MI decision- support in the community; and 2) creating patient-CHW audio recordings, which can then be used by supervisors to help CHWs maintain MI skills, preventing skill decay. Building on our work over the last ten years in rural Nepal, we will develop an mHealth app for CHWs—Community-based mHealth Motivational Interviewing Tool for Depression (COMMIT-D)—that will provide decision-support for MI and capture consented audio recordings of patient interactions for review and feedback by facility-based MI specialists. The scientific premise is based on three well-established behavioral principles: five-step design thinking (iterative stakeholder inputs enhance acceptability and feasibility), social psychology (intrinsic, rather than extrinsic, motivation correlate with positive behaviors), and the MI causal chain model (MI-consistent statements made by CHWs improve patient outcomes). We have already developed facility- and mobile-based digital decision-support tools for depression and other chronic conditions in Nepali. Whereas our existing tools focus on knowledge-based skills, the proposed intervention will focus on communication skills (e.g., assessing the patient’s stage of change and responding in an MI-consistent manner). Using the five-step human-centered design thinking, we will iteratively develop and test COMMIT-D with frequent, structured input from stakeholders. We will then conduct a 6-month pilot trial to study its acceptability and feasibility among patients, CHWs, and their supervisors. We will assess pathways to impact by measuring CHW fidelity to MI principles (using the standard tool MITI), treatment adherence (antidepressants and clinic appointments), and the overall impact on depression outcomes (Patient Health Questionnaire-9 scores). Our team constitutes a ten-year-long collaboration between the research team, the Nepali non-profit healthcare provider Possible, and the Nepal Government. This study will develop and sustain research capacity-building in Nepal by supporting researchers via in-person workshops, online lectures, and mentored research in mHealth, MI, depression, manuscript writing, and ethical conduct of research. If successful, the results from this study will inform a well-powered trial to assess effectiveness and relevance to underserved global populations, including those in the United States.