Abstract
Health and illness fluctuate across a person's life span, and various theories have been developed to address the unique perceptions and situations that accompany these fluctuations. An innovative model of health change resulted from a synthesis of the major concepts from 2 such theories: Mishel's uncertainty in illness theory and the Corbin and Strauss chronic illness trajectory framework. The proposed integrated model, the Health Change Trajectory Model, provides original conceptual definitions that operationalize trajectory framework in the context of changes in health. The use of a health trajectory perspective extends applications of the model to a wide range of health changes that result in uncertainty and ambiguity.