The prevalence of opioid use disorder (OUD) and surge in overdose deaths remain key public health concerns. Despite evidence supporting the efficaciousness of medications for opioid use disorder, most people with OUD do not receive treatment. In this qualitative study, semi-structured interviews were conducted with 35 adults in a northeastern city to learn about their experiences with substance use treatment. Qualitative data were analyzed using an inductive thematic content analysis approach, and a social ecological model was applied to examine contextual factors affecting participants’ experiences accessing and engaging in treatment. While we organized our findings following the individual, interpersonal, community, and society levels of the socio-ecological model, we also observed overlap and interconnectedness between and across these levels. Our findings suggest that retention in treatment often depends upon personal motivation, treatment availability, the match of the treatment modality to an individual’s needs, and social support. A person-centered approach is needed to promote individualized care and tailor treatment components to the patient’s needs.