Lagerkvist was reared in a traditional religious manner in a small town. The influence of his early years remained strong despite his introduction to modern scientific ideas and his eventual break with the religion of his forefathers. He became involved with socialism and soon began to support artistic and literary radicalism, as demonstrated in his manifesto entitled Ordkonst och bildkonst (1913; “Literary and Pictorial Art”). In Teater (1918; “Theatre”), the three one-act plays Den Svåre Stunden (“The Difficult Hour”) illustrate a similar modernist viewpoint.

The extreme pessimism that pervaded Lagerkvist's works during World War I, such as Ångest (1916; “Anguish”), slowly subsided, starting with Det eviga leendet (1920; The Eternal Smile) and his autobiographical novel Gäst hos verkligheten (1925; Guest of Reality), until finally he declared his faith in man in the great prose monologue Det besegrade livet (1927; “The Triumph over Life”), which became a positive point of departure for much of his later work.

When the new creeds of violence were being proclaimed in the early 1930s, he quickly recognized their danger. His prose work Bödeln (1933; The Hangman), later dramatized, is a protest against the everlasting brutality in the world. The play Mannen utan själ (1936; The Man Without a Soul) is also an expression of Lagerkvist's indignation with Fascism. During the 1940s he wrote his most unusual play, sometimes called a “stage oratorio,” Låt människan leva (1949; Let Man Live), which deals with man's readiness throughout history to judge his fellows and condemn them even to death.

It was not until his novel Dvärgen (1944; The Dwarf ) appeared that he had unqualified success with Swedish critics; it became his first best-seller. With Barabbas (1950) he achieved world recognition.

Evening Land=Aftonland (1975) is a literal translation into English by Leif Sjöberg and verse rendering by W.H. Auden of 66 of Lagerkvist's poems. The Marriage Feast (1973) contains English translations of 19 Lagerkvist short stories.