The purpose of this study was to determine the importance of knowledge of clinical background data on nursing assessments of infant pain. In a quasiexperimental design, the infant pain assessments of two groups of pediatric nurses were compared. Both groups assessed the levels of pain of the same videotaped infants. One group also read clinical background data about each infant; the other group did not. The group who read clinical background data evidenced higher mean levels of assessed pain per videotaped infant than did the group who only viewed the videotapes. Findings underscore the importance of clinical data and clinical context in the process of assessing infant pain and the risk of underestimating pain when all factors are not considered.