Born in Bath, England, she was the second of two daughters of Wilmott and Gertrude Provis Houslelander. Several authors, including Maisie Ward in her 1962 biography "Caryll Houselander: That Divine Eccentric," incorrectly state that Caryll was born on October 29, 1901. Caryll was born on September 29, 1901 according to her birth certificate (cited in Andrew Cook, "Ace of Spies: The True Story of Sidney Reilly," rev. ed., 2004, p. 319, n. 27) and her remark in "A Rocking-Horse Catholic" (cited below, p. 41) that she took the confirmation "name of Michael after the Archangel on whose feast day I was born." When she was six her mother converted to Catholicism and she in turn was baptised. Shortly after her ninth birthday her parents separated and her mother opened a boarding house to support the family whilst Caryll was sent away to a convent where she reported her first mystical experience. One day she entered a room and saw a Bavarian nun sitting by herself, weeping and polishing shoes. At this time there was much anti-German sentiment due to the war. As she stared she saw the nun's head being pressed down by a crown of thorns that she was to interpret as Christ suffering in the woman.

In her teens she returned to help her mother in the running of the boarding house. Gertrude allowed a priest to stay and this became a source of scandal such that Caryll and her mother suffered ostracism. This may have been partly influential in Caryll's decision to leave the Church as a teenager, not returning until in her twenties. It may also have contributed to a sense of isolation she would feel at times, reflected in panic attacks when entering rooms and meeting strangers, so much so that she was considered neurotic.

One night in July 1918 Caryll was sent by her mother on an errand. On her way to the street vendor she looked up and saw what she later described as a huge Russian icon spread across the sky. The icon she saw was Christ crucified lifted up and looking down, brooding over the world. Shortly after she read in a newspaper article about the assassination of Russian Tsar Nicholas II. She said the face she saw in the newspaper photograph was the face she saw spread out over the sky as the crucified Christ.

A third vision occurred when she was travelling on a busy underground train when she suddenly saw Christ, living and rejoicing , suffering and dying, in each and everyone of the passengers. When she left the train the mystical experience continued for several days, during which she became convinced that the unity of life in Christ was the only solution to loneliness and the human condition.

Another experience involved one of her doctors who had died who showed up and sat next to her on a bus. They were able to talk and converse.

The three mystical experiences she claimed to have experienced, convinced her that Christ is to be found in all people, even those whom the world shunned because they did not conform to certain standards of piety. She would write that if people only looked for Christ in the "saints" they would not find him. She herself smoked and drank and had a sharp tongue. She returned to the Catholic Church in 1925 but her spiritual reading was founded almost entirely on the Gospels, rather than the Fathers of the Church or official Church documents. She met and fell in love with Sidney Reilly, famous spy and the model for Ian Flemings "James Bond", but he left her broken-hearted when he married another woman. She would never marry.

Houselander was a prolific writer and contributed many pieces to religious magazines such as the "Messenger of the Sacred Heart" and "The Children's Messenger". Her first book, "This War is the Passion", was published in 1941 and in it she placed the suffering of the individual and its meaning within the mystical body of Christ. For a time she became publishers Sheed & Ward's best selling writer drawing praise from people such as Ronald Knox:

"she seemed to see everything for the first time, and the driest of doctrinal considerations shone out like a restored picture when she had finished with it. And her writing was always natural; she seemed to find no difficulty in getting the right word; no, not merely the right word, the telling word, that left you gasping."

During the war doctors began sending patients to Houselander for counselling and therapy. Even though she lacked formal education in this area she seemed to have a natural empathy for people in mental anguish and the talent for helping them to rebuild their world. A visitor found her once alone on the floor, apparently in great pain, that she attributed to her willingness to accept on herself a great trial and temptation that was overwhelming another person.

The psychiatrist Dr. Eric Strauss, later President of the British Psychological Society, said of Houslander: "she loved them back to life"..."she was a divine eccentric".

She titled her autobiography "A Rocking-Horse Catholic" to differentiate herself from those who described themselves as "cradle Catholics". She died of breast cancer in 1954 at the age of 53. Margot H. King is working on a biography for Peregrina Publishers, Toronto, Canada, that will update Maisie Ward's 1962 attempt.

Sheed & Ward books:

• This War is the Passion (1941); republished by Ave Maria Press (2008)
• The Reed of God (1944); republished by Ave Maria Press (2008)
• The Splendor of the Rosary by Maisie Ward, prayers by Caryll Houselander (1945); Houselander's prayers reprinted in The Essential Rosary published by Sophia Institute Press (1996)
• The Flowering Tree (1945)
• The Dry Wood (1947)
• The Comforting of Christ (1954)
• The Passion of the Infant Christ (1949)
• Guilt (1952)
• A Rocking-Horse Catholic (1955)
• The Stations of the Cross (1955) illustrated with fourteen wood engravings by Caryll Houselander.
• The Way of the Cross (1955); revised edition (inclusive language changes and use of a different Biblical translation for Scriptural quotations) published by Liguori Publications (2002)
• Inside the Ark (1956)
• Terrible Farmer Timson and Other Stories (1957)
• The Risen Christ (1959); republished by Scepter Publications (2007)