Innovation Concept: Emergency physicians (EP) rarely receive timely, iterative feedback on clinical performance that aids their reflective practice. The Calgary zone ED recently implemented a novel email-based alert system wherein an EP is notified when a patient whose ED care they were involved in is admitted to hospital within 72-hours of discharge from an index ED visit. Our study sought to evaluate the general acceptability of this form of audit and feedback and determine whether it encourages practice reflection. Methods: This mixed methods realist evaluation consisted of two sequential phases. An initial quantitative phase used data from our electronic health record and a survey to examine the general features and acceptability of 72-hour readmission alerts sent from May 2017-2018. A subsequent qualitative phase involved semi-structured interviews exploring the alert's role in greater depth. Quantitative data were summarized using descriptive statistics and qualitative data were analyzed using thematic and template analysis techniques. Results of both phases were used to guide construction of context-mechanism-outcome statements to refine our program theory. Curriculum, Tool, or Material: 4024 alerts were sent over a 1-year period, with each physician receiving approximately 17 alerts per year (Q1: 7, Q3: 25, IQR: 18). The top five CEDIS complaints on index presentations were abdominal pain, flank pain, shortness of breath, vomiting and/or nausea, and chest pain (cardiac features). The majority of re-admissions (78.6%) occurred within 48 hours after discharge. Immediate alert survey feedback provided by EP's noted that 52.65% (N = 471) of alerts were helpful. Thematic analysis of 17 semi-structured interviews suggests that the alert was generally acceptable to physicians, However, certain EPs were concerned that the alert impacted hire/fire decisions even when leadership didn't endorse this sentiment. Physicians who didn't believe alerts were involved in hire/fire decisions, described greater engagement in the reflective process. Conversely, physicians, who believed alerts were involved in hire/fire decisions, were more likely to defensively change their practice. Conclusion: Most EPs noted that timely notification of 72-hour readmissions made them more mindful of documenting discharge instructions. Our implementation of a 72- hour readmission alert was an acceptable format for audit and feedback and appeared to facilitate physician reflection under certain conditions.