Objective: The objective was to develop a decision aid (DA) to facilitate shared decision making (SDM) around whether to obtain computed tomography (CT) imaging in patients presenting to the emergency department (ED) with suspected uncomplicated ureterolithiasis. Methods: We used evidence-based DA development methods, including qualitative methods and iterative stakeholder engagement, to develop and refine a DA. Guided by the Ottawa Decision Support Framework, International Patient Decision Aid Standards (IPDAS), and a steering committee made up of stakeholders, we conducted interviews and focus groups with a purposive sample of patients, community members, emergency clinicians, and other stakeholders. We used an iterative process to code the transcripts and identify themes. We beta-tested the DA with patient–clinician dyads facing the decision in real time. Results: From August 2018 to August 2019, we engaged 102 participants in the design and iterative refinement of a DA focused on diagnostic options for patients with suspected ureterolithiasis. Forty-six were ED patients, community members, or patients with ureterolithiasis, and the remaining were emergency clinicians (doctors, residents, advanced practitioners), researchers, urologists, nurses, or other physicians. Patients and clinicians identified several key decisional needs including an understanding of accuracy, uncertainty, radiation exposure/cancer risk, and clear return precautions. Patients and community members identified facilitators to SDM, such as a checklist of signs and symptoms. Many stakeholders, including both patients and ED clinicians, expressed a strong pro-CT bias. A six-page DA was developed, iteratively refined, and beta-tested. Conclusions: Using stakeholder engagement and qualitative inquiry, we developed an evidence-based DA to facilitate SDM around the question of CT scan utilization in patients with suspected uncomplicated ureterolithiasis. Future research will test the efficacy of the DA in facilitating SDM.