Advances in fundamental measurement have led to many exciting new deve
lopments in functional assessment. This paper presents fundamental mea
surement theory and method in summary form, and briefly describes its
various applications to functional assessment, program evaluation, and
outcomes analysis in physical medicine and rehabilitation. The implic
ations of computerized medical records and longitudinal patient tracki
ng in national or global computer networks for functional status and h
ealth status gold standards are briefly addressed.