Root cause analysis is often suggested as a means of conducting quality assurance, but few physicians are familiar with the actual process. We describe a detailed approach to conducting root cause analysis, with an illustrative case to explain the technique. By studying how root cause analysis is applied to the case of a missed epidural abscess, the reader will see how the process reveals systems improvements that reduce the risk that such a miss will happen again. Following this process will be helpful in using root cause analysis to fix not just individuals’ issues but also but systemwide quality assurance issues to improve patient care.