This article describes a process evaluation conducted as part of a proof-of-concept study to develop, implement, and test a text messaging program to promote medication and appointment adherence, sexual and substance use risk reduction, general health and well-being, social support, and patient involvement. The text-messaging program was implemented in Chicago, Illinois, at an outpatient medical clinic that promotes the well-being of gay, lesbian, bisexual, and transgender persons. We collected and analyzed qualitative data from patients, providers, and research staff to answer the following questions: (1) What factors of the organizational context were important for implementation? (2) How are implementation policies and practices, organizational climate, and perceptions of implementation effectiveness described by intervention stakeholders? (3) What types of issues related to fidelity occurred during implementation? (4) What recommendations for improvement do stakeholders suggest? The study coordinator, providers, and the patients themselves confirmed that patients liked the messages and program overall. The program was implemented with high fidelity. The primary recommendations for improvements were to enhance confidentiality and implement strategies to lessen message fatigue. The findings from this process evaluation demonstrate the feasibility and acceptability of the intervention from the perspectives of patients, providers, and research staff. A larger-scale intervention study that incorporates these stakeholders' suggestions for improvement is warranted.