Defining healing requires a set of measurements that quantify the physical factors that change during healing. Such a list of measures gives a de facto definition of what constitutes pressure ulcer healing and what influences it. This paper attempts to answer a more specific question: Which measurements are strong candidates for inclusion in a tool for monitoring pressure ulcer healing? Three sets of clinical measurements are analyzed--the assessment proposed by the Agency for Health Care Policy and Research Guideline Development Panel for the Treatment of Pressure Ulcers; the recommendations of the Wound Healing Society; and the Pressure Sore Status Tool. The validity of the 11 clinical measures common across these assessment methods is examined using empiric evidence from studies of wound healing.