Whether the "July effect"—a period of increased risks due to the introduction of new interns and residents at hospitals—is a real phenomenon or merely a myth has been long debated. Prior studies have largely been mixed, although a systematic review concluded that the weight of the evidence suggests increased mortality during this annual workforce transition. This retrospective cohort study used the AHRQ-maintained nationwide inpatient sample database to examine hospital-acquired conditions, which are considered to be never events. Of the nearly 145 million admissions recorded across 4 years, hospital-acquired conditions occurred in 4.7% of hospitalizations overall, while patients admitted in July had an incidence of 4.9%. July admissions were linked to a 6% increased likelihood of experiencing a hospital-acquired condition, with multivariate analysis corrections. Hospital-acquired conditions, which represent preventable complications, are likely a more sensitive marker for hospital quality and safety than mortality. A prior AHRQ WebM&M commentary explored the implications of the July effect through discussing a case of iatrogenic hypoglycemia (a never event) related to a new intern's lack of experience.