I want my readers to understand Leonard Bernstein as a person whose political life was intimately bound up with his artistic life. I was inspired to begin writing this book in 1995, when the FBI’s dossier on Bernstein became accessible under the Freedom of Information Act. To that date, only about five of this dossier’s many hundreds of pages had been published or made use of by biographers. Using these materials in conjunction with Bernstein’s correspondence and other papers that became available at the Library of Congress in Washington, D.C., I have written an account of Bernstein’s life that deepens considerably our understanding of this iconic figure.I set out to document Bernstein’s extraordinary engagement with leftwing politics to a degree far surpassing what other biographers have covered. I go on to document, among others, his tribulations during the 1940s and 1950s blacklist era; his recuperation via the so-called Cultural Cold War; his ascension to the musical directorship of the New York Philharmonic; his political work in the anti-Vietnam War, civil rights, and gay rights movements; his political and social philosophy. I then explain how all of these found connection, if not expression, in Bernstein’s compositions, and in his championing of the works of Gustav Mahler. Focusing on interconnections between politics and culture, I try to indicate why Bernstein, up to his dying day, remained frustrated in his hopes to compose a work of great political significance.