Enter the text here that is the new abstract information for your application. This section must be no longer than 30 lines of text. Project Summary/Abstract Physician opioid prescribing practices are a major upstream contributor to increases in chronic opioid use, opioid addiction and overdose deaths. Opioid prescribing after surgery is an important intervention target, as opioids are commonly overprescribed after surgery, post-operative opioid prescribing is a risk factor for chronic opioid use, and unused opioids prescribed for patients after surgery are an important reservoir of opioids available for misuse and diversion. The scientific premise of our study is research in social psychology and behavioral economics that suggest that people are strongly motivated by social approbation, which makes them want to adhere to prevailing social norms. In other settings, social norms have been used to successfully influence decision making, but have rarely been tested in the healthcare setting and have never been applied in the inpatient setting or with opioid prescribing across a range of conditions. We propose a cluster randomized trial to investigate the extent to which normative information, conveyed through “nudges” within the electronic health record (EHR), can change post-surgical opioid prescribing behavior, and whether the behavior change persists when the nudge is turned off. We will test and compare to usual care different ways of conveying and reinforcing social norms around opioid prescribing, including: (1) providing an injunctive norm at the time of prescribing (prescribing behavior compared to national guidelines); (2) providing the injunctive norm and cumulative feedback on prescribing behavior relative to the norm (i.e., whether or not the provider is a “top performer”) through a monthly email outside of the EHR. To our knowledge, no previous study has investigated the extent to which normative information, conveyed within the EHR, can change opioid prescribing behavior, an important public health goal. By examining the comparative effectiveness of different ways of conveying and reinforcing normative information for diverse practice areas, we also address a scientifically significant research question and advance applied research in social psychology and behavioral economics. With 23 hospitals located in diverse geographic settings and using a common EHR vendor (Epic), our clinical partner, Sutter Health, provides the institutional commitments and sample sizes to deploy and test the proposed nudges in a scientifically rigorous fashion.