What was C.S. Lewis’s final published book, released shortly after his death?

C.S. Lewis’s final published book was Letters to Malcolm: Chiefly on Prayer.

Letters to Malcolm: Chiefly on Prayer was published posthumously in 1964, after Lewis died in November 1963. The book takes the form of letters to a fictional correspondent named Malcolm and explores prayer, worship, church practice, suffering, and ordinary Christian life.

The work is not a collection of private letters to a documented friend named Malcolm. Its epistolary structure is a literary device that lets Lewis develop ideas conversationally, raising questions and answering them through a sequence of imagined exchanges.

Lewis’s death occurred on 22 November 1963, and the book appeared the following year. It is distinct from A Grief Observed, which was published in 1961 under the pseudonym N.W. Clerk after the death of Lewis’s wife, Joy Davidman. The Last Battle was also published earlier, in 1956.