Fifty years ago, Robert Glaser introduced the concept of criterion-referenced measurement in an article in American Psychologist. Its early proponents predicted that this measurement strategy would revolutionize education. But has it lived up to its promise? W. James Popham explores this question by looking at the history of criterion-referenced measurement in education. Four implementation mistakes, he writes, have distorted the use of criterion-referenced measurement: the misconception that criterion-referenced refers to tests instead of test interpretations; the misconception that a criterion is a level of performance instead of a domain of knowledge or skill; the failure to teach and measure a reasonable number of domains; and the tendency to provide too much or too little detail in domain descriptions. If these mistakes were rectified, Popham asserts, criterion-referenced measurement could fulfill its potential and lead to better instruction.