Because of its subjective nature, the assessment of pain requires the use of comprehensive practices that accurately reflect a patient’s experiences of pain. The purpose of this study was to determine how nurses make decisions in their assessment of patients’ pain in the postoperative clinical setting. An observational design was chosen as the means of examining pain activities in two surgical units of a metropolitan teaching hospital in Melbourne, Australia. Six fixed observation times were selected. Each 2-hour observation period was examined 12 times thus resulting in 74 observations. In total, 316 pain activities were determined. Five themes relating to assessment were identified from the data analysis: simple questioning, use of a pain scale, complex assessment, the lack of pain assessment, and physical examination for pain. The study identified how nurses’ prioritization of work demands created barriers in conducting timely and comprehensive pain assessment decisions.