BACKGROUND : Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are life-threatening conditions that may present with similar findings to other severe dermatologic diseases. OBJECTIVE : The primary objective of this exploratory study was to explore factors associated with SJS/TEN and develop a model that provides the predicted probability of SJS/TEN for patients for whom the diagnosis of SJS/TEN is considered. METHODS : Retrospective review of consultations for patients with suspected SJS, TEN, or overlap at 4 academic dermatology consultation services. RESULTS : Overall, 208 patients were included; 59 (28.4%) had a final diagnosis of SJS/TEN, and 149 (71.6%) were given a different diagnosis. The most common mimickers were drug hypersensitivity syndrome (n = 21, 10.1%), morbilliform drug eruption (n = 18, 8.7%), erythema multiforme (n = 15, 7.2%), and acute generalized exanthematous pustulosis (n = 13, 6.2%). Nikolsky sign, atypical targets, fever, and lymphopenia were included in a model for predicting the probability of SJS/TEN. CONCLUSIONS : All cases were obtained from academic centers, which may limit the generalization of findings to community-based settings. This was an exploratory study with a small number of cases, and external validation of the model performance is needed. CONCLUSIONS : Early dermatologic evaluation of patients with suspected SJS/TEN is key to separating patients with this condition from those who ultimately receive diagnoses of other serious skin diseases.