fforts to curb unsustainable growth in US health care spending have focused on reducing the estimated $76 to $101 billion spent on low-value care, which is defined as services that provide no or minimal benefit to patients in specific clinical situations. 1 To this end, the American Board of Internal Medicine Foundation and Consumer Reports launched the physician-led Choosing Wisely campaign in 2012 to encourage awareness, measurement, physician accountability, and intervention around this problem. Nine years later, the US Choosing Wisely compendium of recommendations for tests and treatments to avoid has grown from 45 to more than 600. The recommendations have been translated into physician, hospital, and system-level quality met-rics and multiservice indices. 2,3 They have been used by clinical leaders to direct policies and interventions 4 and payers to guide utilization management of low-value services. 5 Choosing Wisely has also expanded to more than 20 countries in North America, Europe, Asia, and South America, becoming the prism through which efforts to reduce low-value care are viewed worldwide. [6][7][8] Despite the wide reach of the Choosing Wisely campaign and its success at raising awareness, 6,8 progress in reducing low-value care use and spending has been modest at best, 9,10 which may be partially explained by the characteristics and expected impact of the services identified in these recommendations. By design, the Choosing Wisely campaign did not IMPORTANCE The US Choosing Wisely campaign has had substantial reach in mobilizing efforts to reduce low-value care, achieved largely by engaging physician specialty societies in stewardship. While some early recommendations were criticized for avoiding revenue-generating services, there is limited evidence of how the composition of recommendations shifted as more societies contributed. OBJECTIVE To analyze the characteristics and expected impact of Choosing Wisely recommendations. DESIGN, SETTING, AND PARTICIPANTS This qualitative study included content and trend analyses of all 626 Choosing Wisely recommendations by US physician societies as of March 1, 2021. Data were analyzed between March and May 2021. MAIN OUTCOMES AND MEASURES Primary outcomes were proportions of identified low-value services by characteristics (society type, service type, indication, do vs avoid, and clinical context) and expected impact (effect on the revenue of society members, cost, number of individuals at risk, direct harm potential, and cascade potential). RESULTS Low-value services identified in the 626 Choosing Wisely recommendations largely covered imaging (168 [26.8%]) and laboratory studies (156 [24.9%]) in the context of chronic conditions (169 [27.0%]) and healthy patients with risk factors alone (126 [20.1%]).Most of the identified low-value services were revenue neutral for the recommending society (402 [64.2%]) and the plurality were low cost (<$200; 284 [45.4%]); low-cost services represented a growing share of low-value services identified by Choosing Wisely re...