Nursing staffing has long been recognized as a significant variable in a hospital budget even through the era of increased productivity and efficiency. In addition, patient acuity has been rising, and increasing demands on nursing personnel have been documented. These increased demands have affected nurse staffing, patient outcomes, and nurse retention, all of which have an impact on our healthcare system. Therefore, it is imperative that nursing time and work be examined in the acute rehabilitation setting—a setting in which research has been sparse. To estimate patient acuity, the activities of nursing personnel must be examined to establish timeframes for the care needed by patients. Previous studies have examined time and work according to pre-established patient acuity categories. California has passed legislation that requires mandatory nurse-staffing ratios in response to the concerns about the adequacy of patient care and safety. We did this study to assess the time and work related to patients with different diagnoses that are typically found in a rehabilitation unit. The data collected can be used to develop a patient acuity system. This study sought to identify how nurses spend their time so that hidden costs and important interventions can be addressed by an institution 's administration.