Medication-taking behavior can significantly affect a patient’s health outcomes. Thus, understanding the extent of and barriers to medication adherence are important in informing development of appropriate interventions to ultimately improve patients’ health outcomes. The use of mixed-methods research designs in pharmacy practice and health services research has grown steadily in the last decade. Within this case study, we will share our experience of using a convergent mixed-methods design to investigate the extent of and barriers associated with medication nonadherence in Qatari primary care settings among patients with type-2 diabetes mellitus. Briefly, we captured quantitative data (prevalence of nonadherence and associated factors) using a validated questionnaire, and qualitative data (barriers to medication adherence) using one-to-one interviews with patients and health care providers. This case study also discusses the challenges encountered and practical lessons learned relevant to this experience.