In 1965, McCay Vernon drove a stake through the heart of the long-established "truth" that deaf people were inferior to hearing people. Launched by Aristotle, emboldened by the 1880 Conference of Milan, and reiterated in the twentieth century through the biased research of many psychologists, this falsehood persisted until the publication of this classic review paper. Vernon succinctly spotlights biases in IQ assessment of deaf children resulting from improper testing methods, research participant sampling, even the experience level of the evaluators themselves. Brief and scholarly, the paper had enormous impact not only on future research regarding cognition and deaf people but on clinical practice as well. Within this paper, insights are evident which Vernon has continued to elucidate throughout his long career. He was arguably the first psychologist to view the deaf population as a heterogeneous one, noting how various hearing loss etiologies differentially affect cognition and other psychological characteristics. His later research, notably that which focused on rubella, deaf blind, and deaf forensic populations, has been similarly pioneering. McCay Vernon's extensive professional impact stems not only from his prolific, readily applied research work but also from his generous and vigorous activities as a teacher, a mentor, and advisor.