Abstract

While “function” is often measured in terms of individual ability, a closer look at the history of wellestablished assessment tools and future directions in assessment show us that a focus on intrinsic factors is not enough. In a number of fields, the theory of “congruence” provides an important model to see that “fit” (or function) is always the product of a dynamic relationship between individual ability and environmental demands. But, as we embrace movements to promote “successful” and “active” aging through the transformation of communities and cities, more work is needed to measure how a range of extrinsic factors (cultural, social, economic, and physical) impact the expression of disability and actually support or improve function.