Howard Andrew Knox (1885-1949) served as assistant surgeon at Ellis Island during the 1910s, administering a range of verbal and nonverbal tests for the mental capacity of potential immigrants. An early proponent of nonverbal intelligence testing (largely through the use of formboards and picture puzzles), Knox developed an evaluative approach that informs the techniques of practitioners and researchers today. Whether adapted to measure intelligence and performance in children, military recruits, neurological and psychiatric patients, or the average job applicant, Knox's pioneering methods deserve in-depth investigation that situates his discoveries within contemporary psychological practice. Completing the first biography of this unjustly overlooked figure, John T. E. Richardson, former president of the International Society for the History of the Neurosciences, takes stock of Knox's understanding of intelligence and his legacy beyond Ellis Island. Consulting published and unpublished sources, Richardson establishes a chronology of Knox's life, including details of his medical training and his time as a physician with the U.S. Army. He describes the conditions that gave rise to intelligence testing, including public concern that the mentally unfit were allowed to settle within the country. He then recounts the development of intelligence tests by Knox and his colleagues and the publication of their research, which captured the attention of a nation. These publications present a useful and extremely human portrait of psychological testing and its limits, particularly regarding the predicament of the people who were examined at Ellis Island. Richardson concludes with the continuation of Knox's work and its changing application in conjunction with modern psychological theory.