Despite decades of research, hospitalized children continue to suffer from unrelieved pain. Failure to apply state-of-the-art knowledge to clinical practice has been termed one of the greatest paradoxes in modern medicine (Kenny, 2001). Clearly, effective pain management requires state-of-the-art knowledge about the pain experience. This article reviews research over the past two decades related to the predictors of age, gender, prior pain experiences, pain expectation, pain acceptance, and pain tolerance. The review underscores implications for clinical practice and indications for future research.