This short research report focuses on psychologist Leon Kamin, who is best known for his research on what became known as the Kamin (blocking) effect. In the 1970s and 1980s he became prominent both inside and outside of psychology, not for laboratory research but for his writings on the heritability of intelligence. Kamin was no stranger to political activism. He joined the Communist Party U.S.A. at age 17, when he was a sophomore at Harvard. By 1949, he was writing for the Daily Worker (pen name: Leo Soft) and was employed as its New England editor in 1949-1950. In January 1954, Kamin was called to testify by Joseph McCarthy's anti-Communist Senate subcommittee, which was visiting Boston and justified its interest in Harvard by citing its winning research grants from the U.S. Department of Defense. Kamin refused to "name names" and he was indicted for contempt of the Senate. (PsycInfo Database Record (c) 2022 APA, all rights reserved).