Small‐scale trials of the Personalized System of Instruction (PSI) in physics at MIT under the sponsorship of the Education Research Center were followed by adoption of large‐scale introductory PSI courses in the Department of Physics. After four semesters, all introductory physics PSI courses were suspended. This study investigates what happened. We point out organizational difficulties in going from small‐ to large‐scale use of the PSI method. We also identify certain conflicting perceptions among participants and observers that contributed to the suspension. The study, we hope, is an example of an informative ’’postmortem’’ of a type much needed in higher education.