Researchers studying opioid use disorder (OUD), especially among populations who have been arrested or incarcerated, have a difficult time recruiting and retaining participants to studies. Similarly, researchers and policymakers have a difficult time ensuring that patients with OUD stay engaged in clinical care services, such as medications to treat OUD. New forms of digital data, including cell phone mobility data, might be incorporated into models to improve research participants’ identification, retention, and engagement in clinical care services. For example, cell phone mobility data, which provide data on where individuals move throughout their daily lives based on carrying a cell phone, have been hypothesized as being able to inform people’s movement and location patterns (to assist in identification for recruitment and retention), their access to and engagement in care, and reasons for loss-to-follow-up in research. However, before collecting and incorporating the use of cell phone mobility data in research and clinical care, especially among sensitive populations with OUD, it is important to study the feasibility and acceptability (including potential ethical concerns) among these populations. Through qualitative interviews, this project will explore the feasibility and acceptability, including potential privacy concerns, of using cell phone mobility data to inform research among populations with OUD, including justice-involved populations. Research questions include: (1) Will participants with OUD be willing to provide access to their cell phone mobility data for OUD-related research and clinical care? And (2) What potential ethical concerns, including privacy and informed consent, need to be addressed and how can they best be addressed in future research on this topic?