Career
He wrote biographies and books on Swedish literature. In 1907, Fredrik married Tora Olsson. Their son Klas Böök (born 1909) became head of the Bank of Sweden and later an ambassador.
Alongside Henrik Schück, Böök was for decades the most influential (and feared) Swedish literature scholar and critic.
He reviewed books for the newspaper Svenska Dagbladet, succeeding Oscar Levertin. During World World War II, Böök actively supported the cause of Germany as a belligerent power.
After the war he lost his dominating role in the literary field His biography was written in 1994 by Svante Nordin.