Context: Providing students reliable objective feedback regarding their clinical performance is of great value for ongoing clinical skill assessment. Since a standardized patient (SP) is trained to consistently portray the case, students can be assessed and receive immediate feedback within the same clinical encounter; however, no research, to our knowledge, has documented the reliability of the SP at assessing student performance. Objective: To determine if SPs provide a reliable assessment of athletic training students' performance in obtaining a patient history and completing a physical examination relative to athletic training faculty. Design: Reliability study. Setting: Athletic training simulation lab. Patients or Other Participants: Two SPs and 2 athletic training faculty assessed 35 students (n = 20 junior; n = 15 senior) in athletic training cohorts from a public liberal arts institution in southeast United States. Intervention(s): Athletic training students completed 2 SP encounters per semester throughout 1 academic year in the athletic training program, totaling 4 SP encounters. Main Outcome Measure(s): After each SP encounter, athletic training faculty and SPs completed the same clinical performance checklist developed specifically for each encounter. The checklist included yes/no items related to obtaining a patient history (10-12 items each) and completing a physical examination (12-15 items each). For each SP encounter, composite scores were computed for both history and physical examination items from the athletic training faculty and SPs. Intraclass correlation coefficients (ICC) determined interrater reliability between athletic training faculty and SPs for history and physical exam items. Results: Reliability coefficients between the SP and athletic training faculty indicated fair to strong agreement for most history and physical examination items. Significance was found for history items in the cervical spine emergency (ICC = 0.671, P = 0.002), knee (ICC = 0.696, P = 0.003), low back (ICC = 0.622, P = 0.002), concussion (ICC = 0.764, P = 0.004), general medical (ICC = 0.571, P = 0.008), and psychosocial intervention (ICC = 0.572, P = 0.008) encounters. The reliability coefficients were significant regarding physical exam items for the cervical spine emergency (ICC = 0.588, P = 0.01), low back (ICC = 0.766, P > .001), concussion (ICC = 0.792, P = 0.001), and general medical (ICC = 0.878, P > 0.001) encounters. Conclusions: Overall, the SPs provided a reliable assessment of the athletic training students' clinical performance for obtaining a patient history and completing a physical examination. Given these results, devoting additional time during SP training should increase the reliability of the SP.