Pain assessment conventionally has been viewed hierarchically with self-report as its "gold-standard." Recent attempts to improve pain management have focused on the importance of assessment, for example, the initiative to include pain as the "fifth vital sign." We question the focus in the conceptualization of pain assessment upon a "vital sign," not in terms of the importance of assessment, but in terms of the application of self-report as a mechanistic index akin to a biologic measure such as heart rate and blood pressure. We synthesize current inclusive models of pain and pain assessment and propose a more comprehensive conceptualization of pain assessment as a transaction based on an organismic interplay between the patient and clinician.