Assessment as it is lived in American schools has changed its role. The humane dimension of teacher know-how, in assessment, has been replaced by quantitative performance assessments that play a political function, as it is the case in a number of countries. This essay discusses it from a critical perspective considering research on the validity of standardized performance tests. Teachers’ field assessments tend to integrate the human factor as a major consideration, to the contrary of standard ized measures that re-shape teaching to match the demand of the law makers. The current tendency in the field of school assessment places Ins tru mental Reason to its extreme, as if machines and bureaucratic criteria could replace the human agents. Because it enforces assimilation, it an carry a wide prejudice to linguistic minor ities. Assess ment is always relative enterprise, as it depends upon a concep tual interpretation and the context of its application. A more humane and deeper approach of evaluation is proposed.