The Peter Garland Papers and Records contain materials related to Garland's various endeavors as an author, avant-garde composer, and publisher. Notable Garland works present include his first book of essays, , and the shadow puppet theatre work, . It also has a large volume of correspondence from family, friends, and colleagues. Many composers who were published in are represented by scores and other writings. The collection is divided into six series: I. Works, 1968-1995; II. Soundings Press, 1971-1997; III. Correspondence, 1968-1997; IV. Personal and Career-Related, 1968-1997; V. Serials, 1969-1997; and VI. Works of Others and Related Material, ca. 1920s-1997.

Series I. Works is divided into three subseries: A. Books, B. Shorter Works, and C. Music. Subseries A. is primarily comprised of longer, non-fiction works written by Garland and published by Soundings Press. There are drafts, early versions, and production materials relating to two of Garland's books of essays: and . There is a full typescript draft of , a collection of autobiographical essays written by Garland during his world travels from 1991 to 1995, and later published by Frog Peak Music. This subseries also contains materials for two works edited by Garland and published by Soundings Press. The most notable of these is .

Subseries B. contains many shorter articles, essays, and reviews written by Garland in the course of his career. The bulk of the materials are handwritten and typed drafts. Similar published pieces by Garland are located in Series V., in periodicals such as and .

Subseries C. Music covers Garland's musical output from 1968 to 1994 with the bulk of the scores from the 1970s and early 1980s. Many of the earliest compositions are graphic scores, which consist primarily of pictures and written instructions. Some of the works represented have been recorded by other performers, including Guy Klucevsek and Aki Takahashi. The two largest individual groups of materials in the subseries are for Garland's two theatre productions, and . For these, there are drafts, scores, and production materials related to the shows, including some photos of the puppets and staging.

Series II. Soundings Press, is divided into three subseries. Subseries A. Issues, contains small amounts of drafts and publication materials for all but two issues of . Most of the correspondence with contributors has been removed to the Correspondence series, and most of the scores for each issue have been removed to the Works of Others section of the collection.

Subseries B. Production Material is comprised of production materials related to various Soundings Press publications. These include catalogs of works published by the press, as well as the handwritten mailing lists for .

Subseries C. Business Papers contains account statements, invoices, and other materials relating to the business side of Soundings Press. There are a large number of maps and other materials that were in Garland's desk when he closed Soundings Press.

Series III. Correspondence is divided into three subseries. Subseries A. contains outgoing correspondence, organized by date. There are copies of some letters to the editor that Garland sent to local newspapers, some responses to articles by other writers, and a few letters regarding grant applications. There is very little outgoing correspondence of a personal nature.

Subseries B. Incoming, Alphabetical, contains correspondence of both a personal and business nature. Many modern composers and musicians from around the world are represented, including John Luther Adams, Harold Budd, John Cage, Lou Harrison, violinist and composer Malcolm Goldstein, pianist Herbert Henck, Larry Polansky, James Tenney, and pianist Aki Takahashi. Many of the composers submitted works to and were also friends of Garland. Particularly notable is correspondence from the composer Conlon Nancarrow, best-known for his works for player piano. Garland helped to return Nancarrow to American music by publishing his collected works, both in and as separate Soundings Press volumes. There is also correspondence with Paul Bowles. Garland published some of his previously unpublished musical works. Extensive correspondence with Betty Freeman, a philanthropist who helped to support Garland and Soundings Press through regular monetary grants, is also present.

Subseries C. Incoming, Chronological, is comprised of correspondence from various correspondents. Some of the represented correspondents include the composer and author Pauline Oliveros, pianist Yvar Mikhashoff, composers Lois Vierk (1988), Mary Jane Leach, and Alvin Lucier, and pianist Bennet Lerner (1983).

Series IV. Personal and Career-Related comprises various materials collected by Peter Garland throughout his career. Included are clippings and reviews concerning Garland and his works, as well as programs and concert announcements relating to Garland and/or his works. In addition to Garland-related programs, there are also numerous programs of concerts related to others, some of which Garland attended. Also noteworthy are photographs of many composers that were used in and other Soundings Press publications.

Series V. Serials includes a full set of , as well as various other music-related publications. Some of these are single issues that include works by friends of Garland.

Series VI. Works of Others and Related Materials primarily consists of musical scores and writings of others, some of which were submitted to and used in . Several composers are particularly well-represented, including John Luther Adams, Paul Bowles, Henry Cowell, David Mahler, Conlon Nancarrow, Larry Polansky, James Tenney, and Joseph Weber. Some other notable composers who are represented are Lou Harrison, Peggy Glanville-Hicks, Ruth Crawford, and Alejandro Caturla.