Preventing adverse events in hospitalized patients is a priority goal of patient safety programs. In-facility falls and in-facility suicide are 2 priority conditions that are thought to be preventable. One-to-one sitters or constant observation is an intervention that has long been used, rooted in tradition: staff that are immediately at hand can help prevent a fall or redirect a patient from engaging in a harmful act. However, one-to-one sitters is a costly intervention, and evidence that it is effective is uncertain; hence, VA policymakers asked for an up-to-date review to inform policy and practice.