First an overview is given about the actual national and international situation concerning standardized testing. Then two major reasons are presented why accountability systems based on standardized testing have become so widespread: (a) the missing validity and reliability of teachers' assessment of students' achievement, and (b) the important role standardized testing plays for output management in educational systems. On the basis of these considerations Alfred North Whitehead's critical remarks on external standardized testing are presented. Whitehead's main point is that external standardized testing limits the freedom of teachers to adapt to the complex, situation specific circumstances in order to obtain a maximum of the creative learning process for students who are conceived as specialists. Instead external testings lead to "teaching to the test." As a consequence, the attitude of creative, adventurous exploration is undermined and substituted by simple pattern recognition, narrow visions, and even boredom. Finally, the question is raised whether there is any possibility of developing a measurement tool which on the one side meets scientific test criteria, and on the other side is still flexible enough to do justice to needs of individual schools--which according to Whitehead are the essential educational unit-- and not vice versa, as it is the case at present with external standardized testing. That such a flexible approach to evaluation is possible is demonstrated by the presentation of the basic ideas of the MSS (Module Approach to Self-Evaluation of School Development Projects) which has been developed and examined in ten schools by the author and his collaborators.