Objective Physical restraints are used in emergency departments (EDs) to address behavioral emergencies in situations in which less restrictive methods have failed. The objective of this study was to evaluate for associations between patient/visit characteristics and physical restraint use. Study Design This study was designed as a cross-sectional, retrospective study of all encounters at Kaiser Permanente Northern California EDs from January 1, 2016, to December 31, 2019, to evaluate differences in patient and visit characteristics between visits involving physical restraint use and those without. Methods Using electronic health record data, this study identified physical restraint use among ED encounters and extracted demographic, clinical, and facility characteristics. The authors calculated odds ratios for physical restraint placement, adjusting for patient and visit characteristics and accounting for within-patient clustering. Results Among 4,410,816 encounters (representing 1,791,673 patients), 6369 encounters (0.1%) involved physical restraint use among 5,554 patients (0.3%). Variables associated with the lowest odds of physical restraint included female sex, presentation to the ED in more recent years, and presence of intentional self-harm/suicidal ideation. Variables associated with the highest odds of physical restraint included higher visit acuity and weekend presentations to the ED. Discussion This study, which leveraged a large, diverse patient sample generalizable to the Northern California population, found several patient and visit characteristics associated with physical restraint use in the ED. Conclusion Results of this study may help identify patient groups and situational factors that are most likely to lead to physical restraint use and structural factors contributing to disparities in care, thereby informing interventions to reduce physical restraint use when possible.