Fear of Communist infiltration into American society was often the FBI's shaky justification for trailing renowned activists. Among the 16 "subversives" whose files are presented here in facsimiles are Cesar Chavez, Harvey Milk, Hedy Epstein, Malcolm X, Howard Zinn, feminist Betty Freidan, Planned Parenthood founder Margaret Sanger, and Abbie Hofmann, who is described as "armed and dangerous." Martin Luther King was perhaps the agency's favorite target, and it is intriguing here to read an extensive account of the civil rights leader's meeting with J. Edgar Hoover.