Introduction: Unnecessary care is an increasingly commonly used term in medicine. Previous survey research suggests that definitions of unnecessary care vary within and among professional and patient groups. This research explores how emergency physicians and administrators understand the term unnecessary care. Methods: Site chiefs and emergency physicians in an Alberta region were recruited through email and online surveys respectively for a qualitative study. One hour one-on-one in-depth interviews explored understandings of unnecessary care within the emergency department (ED) context. Interview transcripts underwent thematic analysis. Results: Five physicians and seven site chiefs completed interviews. Two key themes emerged. First, interviewees conceptualized unnecessary care as inappropriate or non-urgent presentations. This patient-centric view raised non-urgent ED presentations as a health system problem with complex components, including: lack of public knowledge of healthcare resources, shrinking comfort and scope of community providers and patient willingness to utilize other resources. Despite concerns over non-urgent visits, interviewees expressed that these patients still need to be seen, assessed and managed. The second conceptualization focused on over-investigation (and to lesser extent, treatment). This physician-centric conceptualization identified issues around: variation in physician risk tolerance, established decision rules with the allowable miss rates, patient expectation for testing or physician feeling that the patient was owed something or that patient would not accept their diagnosis/treatment without testing. Additionally, interviewees described patient characteristics that may initiate more aggressive investigation (e.g., patient reliability, follow-up care access, etc.). An overarching concern about the connection between unnecessary care and wasted resources was identified. Additionally, interviewees emphasized that patient conversations are outside the scope of unnecessary care despite their possible implications for limited time resources. Conclusion: A range of concepts surrounding unnecessary care in the ED were identified. Further exploring nuances of these conceptualizations may inform and improve the effectiveness of campaigns seeking to improve efficiency in practice and reduce inappropriate care. Additionally, this work provides an impetus for developing clearer concepts of care within the ED.