Nurses, nurse’s aides, and physicians were presented with vignettes describing elderly patients and were asked to assess their level of pain from four external cues (facial expression, verbalizations, avoidance of movements and positions, and interpersonal contact) in three conditions: when the illness was not known, when it was known to be arthritis, and when it was known to be cancer. For all health caregivers, the most important cue for judging pain was patients’ facial expression. When the nature of the illness was not known, the impact of this cue was stronger than when the nature of the illness was known.