The purpose of this study is to develop a change-sensitive scale for evaluating developmental change in visual-motor ability across the life span. A partial-credit item-response model is used to estimate theta values for each age group between 4 and 90 using the Bender-Gestalt II standardization sample (N = 4,000). Results from this study suggest that visual-motor ability has a rapid maturation lasting into middle adolescence, steadily decreases through adulthood, and rapidly declines in later age ranges. These results provide evidence against previous research conclusions that suggested visual-motor ability development ends in late childhood and remains steady across the life span. A case study is provided to demonstrate the practical use of the change-sensitive scale in monitor intervention outcomes. (Contains 7 tables and 2 figures.)