The Minnesota Multiphasic Personality Inventory (MMPI) was developed at the University of Minnesota, Minneapolis, in the 1930s and 1940s. It became a highly successful and highly controversial psychometric tool. In professional terms, psychometric tools such as the MMPI transformed psychology and psychiatry. Psychometric instruments thus readily fit into the developmental history of psychology, psychiatry, and neurology; they were a significant part of the narrative of those fields' advances in understanding, intervening, and treating people with mental illnesses. At the same time, the advent of such tools also fits into a history of those disciplines that records the rise of obsessional observational and evaluative techniques and technologies in order to facilitate patterns of social control that became typical during the Progressive Era in the United States and after. It was those patterns that also nurtured the resistance to psychometrics that emerged during the Vietnam War and after.