When Pepper Stetler was told that her daughter who has Down Syndrome would be regularly required to take IQ tests to secure support in school, she asked a simple question: why? In questioning the authority and relevance of the test, Stetler sets herself on a winding investigation into how the IQ test came to be the irrefutable standard for measuring intelligence. The unsettling history causes Stetler to wonder what influence this test will have over her daughter's future and whether Louisa should be taking it at all.

As she uncovers the history of IQ, exposing its roots in eugenics, racism, xenophobia, and ableism, Stetler realizes that the desire to quantify intelligence is closely tied to a desire to segregate society. She traces its legacy from inception to present day, where schools and society have adopted the IQ as shorthand for an individual's aptitude—in essence, their worth. Stetler questions how this rigid definition of intelligence has influenced who society holds up as successful and what we miss when we judge someone on their measured intelligence.

A Measure of Intelligence investigates the origins and influence of the IQ test on our education system, questions how we define and judge intelligence, challenges its flawed foundation, and argues for a reevaluation of how we understand an individual's perceived potential.