Psychometric and descriptive perspectives of illness impact over the life span. This article describes the development of an instrument that quantifies illness over the course of life. The sample was comprised of 308 women, aged 50 to 70, who were alumnae of a master's program in nursing. Each submitted information concerning illness experienced during each decade of life. Each time period was then rated multidimensionally (Duration, Discomfort, Interference, Threat to Life) to reflect the impact of the various conditions and the means by decade (Decade Impact) were computed. In general, after the first two decades, magnitude of ratings increased with age, indicating greater disease impact. Interrater reliability and internal consistency reliability of the scale were high. Evidence for construct validity included substantial differences between those with and without specific illness conditions, as well as correlations with hospitalization history and health self-ratings. In cluster analysis of patterns across decades, five distinct patterns emerged into which subjects were grouped. 