The collection spans the years 1838 to 1998, with the bulk dating from 1838 to 1972. The material consists of correspondence, prose, poetry, lecture and music manuscripts, photographs, memorial information, and newspaper clippings.

The correspondence gives a rounded picture of Lanier's life and work. Many of his outgoing letters as well as incoming are included in this collection. Most of Lanier's adult life was marked by a continuous struggle against poor health and financial straits. He was forced to undertake many journeys for the sake of his health, and his efforts to support himself and his family were a constant strain. The correspondence between Lanier and his wife and family present a vivid portrait of his personality.

Lanier's letters begin during his days as a Confederate soldier and prisoner-of-war, but most letters are from 1870 through 1881. During the period 1873 to 1877 when Lanier spent the fall and winter in Baltimore, his letters detail his musical and literary activities in that city. People mentioned include Leonce Rabillon, Innes Randolph, William Hand Browne, Edward Spencer, John Banister Tabb, Richard Malcolm Johnston, Severn Teackle Wallis, Henry Wysham, and Otto Sutro. Lanier's incoming letters from friends and fellow musicians and authors complement Lanier's letters to his family. Musicians with whom Lanier was in contact included Mme. Auerbach, Dudley Buck, Asger Hamerik, Theodore Thomas, and Carl Wehner.

Through the efforts of Lanier's family after his death, the collection contains nearly all Lanier's extant prose, poetry, and music manuscripts. There are drafts, finished manuscripts, proofs, and printed copies. These are found in Series 4, 5 and 10.

A considerable portion of the collection deals with Lanier's family's efforts to have him and his work recognized. Series 7 Memorials contains letters, clippings, a video, and printed material from numerous celebrations held in Lanier's honor. Mary Day Lanier's correspondence outside of her letters from Sidney largely deal with her efforts to have Lanier's work published.