OBJECTIVES:  To evaluate the current list of Choosing Wisely recommendations, and assess the quality and quantity of evidence used to characterize “low value” services. METHODS:  All recommendations presented on the Choosing Wisely initiative’s website were identified, along with the references that accompany each recommendation. In addition to standard reference elements, Medical Subject Headings and MEDLINE publication type assignment data were collected. References not indexed in Pubmed were verified using online websites to obtain complete details pertaining to the source and type of publication. RESULTS: The Choosing Wisely initiative consists of 475 recommendations produced by 74 specialty societies. Each specialty society describes recommendations in detail and presents evidence supporting that determination. All included specialty societies describe the process by which their recommendations were developed. A variety of clinical services were targeted by Choosing Wisely recommendations. The majority (238, 50.1%) were clinical tests that relate to patient diagnosis, prognosis, or monitoring. The quality, quantity, and applicability of the cited evidence were highly variable. A total of 1,768 citations were retrieved. Out of 1,548 peer-reviewed references, 77.71% were published between 2005 and 2016. Clinical guidelines (578, 32.7%) and real world evidence (405, 22.9%) represented the most common types of evidence. 89 (18.7%) specialty society recommendations made economic claims of cost or value; however, only 20 (22.47%) cited supporting economic evidence. CONCLUSIONS: These findings suggest that the Choosing Wisely initiative’s recommendations should be based on systematic reviews of the evidence and should be developed in a structured, clear, and transparent manner. Clear evidentiary justification for the selection of low value services is necessary for the ongoing success and sustainability of the Choosing Wisely initiative. Potential explanations for the observed variation include the amount of evidence available, the thoroughness of the relevant specialty society, and the evolving nature of the clinical evidence base.