This collection spans the whole of Peter Brown's professional career from 1974 to 2003. The Personal materials series includes items created during his time as a doctoral student at Northwestern University including a concert band program and schedule, several reviews written about his various books, and concert programs from Indiana University to which he contributed program notes. This series also includes his most recent curriculum vitae, dated one year before his death. The list of correspondents is quite lengthy, including many journal editors, publishers, librarians, and musicologists. Among these correspondents are: David Wyn Jones, Leonhard Scheuch, Andreas Jaschinski, Robert Schuneman, Walter Schenkman, Craig Parker, Somfai László, William S. Newman, Jan LaRue, H.C. Robbins Landon, Gerda Mraz, Herman Lang, Denes R. Betha, Eugene K. Wolf, James Webster, Vernon Gotwals, and Georg Feder. This series also includes correspondence with representatives of the Indiana University Foundation regarding possible donors for endowment funds for the musicology department.

The second series in this collection contains records relating to Brown's graduate education, student assistantships, and work on his dissertation. In the notes sub-series are Brown's notes on H.C. Robbins Landon's Romantic Crisis in Austrian Music as well as note on the stylistic periods of the medieval ages, the Renaissance, Classical period, Romantic period, and the Mannheim Symphonists. Brown also retained files on several 20th century composers. In addition to the well-known composers such as Milton Babbitt, Elliott Carter, Lukas Foss, Ned Rorem, and Ian Xennakis are the somewhat lesser known composers Roy Harris, David Barger, William Bergsma, and Marc Blitzen. The sub-series encompassing materials created during Brown's teaching assistantship at Northwestern University include lecture notes, handouts, and transparencies discussing the music of Bach, Beethoven, Berg, Berlioz, Chopin, Debussy, Mozart, Sammartini, Verdi, and Wagner. The final sub-series under Education contains materials relating to Brown's Ph.D. dissertation "The Solo and Ensemble Keyboard Sonatas of Joseph Haydn: A Study of Structure and Style." This sub-series includes Brown's early notes and music examples as well as annotated drafts of the dissertation chapters.

Flowing from the Education series is the third series of the collection, Teaching materials. Within the first sub-series of course materials are items such as syllabi, exams, handouts, and lecture notes. Some of the courses represented here include Introduction to Musicology, Haydn, Survey of Music Literature, Mahler, Piano Literature, Mozart's Operas, and The Symphony. The second sub-series, doctoral advisory materials, includes materials related to Brian Hart's dissertation. The subject files sub-series contains notes and handouts relating to course topics.

The fourth series contains items relating to various grant applications and projects. Included in the series are records related to a Guggenheim fellowship. The majority of the series, however, is dedicated to the National Endowment for the Humanities (NEH) grant that allowed Brown to conduct his seminar titled "Patterns of stylistic development in Haydn's music."

Comprising a large portion of the collection is the Writings series. The first sub-series, articles, includes edited drafts for most of Brown's numerous articles. Also found here are some drafts which appear to have not been published, including "Joseph Haydn in Context," "Haydn's Secular Vocal Music," Marianna Martines' Autobiography as a new Source for Haydn's Biography," and "Male Composers, Female Performers, and Haydn's Keyboard Music." Brown's articles are followed by a sub-series dedicated to his books, including Haydn: The Creation, (Edited by A. Peter Brown, August Eberhard Müller, Gottfried van Swieten, and John Milton. New York: Oxford University Press, 1995), Joseph Haydn's Keyboard Music: Sources and Style, (Bloomington, IN: Indiana University Press, 1986), and volumes two through four of the four-volume set Symphonic Repertoire. Included among these book materials are numerous edited drafts and proofs. While most of the editorial markings are anonymous, there is some correspondence with Christopher Hogwood regarding Haydn: The Creation, as well as drafts edited by Bertil van Boer, A. Bland, Reindl, and Luis F. Lopez. Brown's book materials are followed by the sub-series labeled conference papers. In addition to the often annotated reading copies of his papers, the conference papers sub-series also includes cassette tapes and slides of his musical examples. This is followed by a sub-series of liner notes and programs. Brown wrote liner notes for Decca and DGG. This sub-series also includes his transcripts for the P.B.S. program "Of Sound and Music." The writings series is closed out by a number of Brown's reviews of books by his contemporaries. Authors of books he reviewed include Manfred Huss, Jan LaRue, Simon Keefe, Sandra Rosenblum, and Neal Zazlaw.

By far the most extensive part of the collection is the series Research materials. The series begin with a sub-series of materials relating to volume three of Symphonic Repertoire. Included are Brown's notes on the composers represented by the volume, such as Bach, Balikirev, Benda, Berlioz, Dvořák, Lizst, and the Russian Five, among several others. This is followed by a sub-series of author files, consisting of annotated articles by several authors. In addition to articles by many of Brown's correspondents, also represented within this sub-series are Theodor Albrecht, Carl Dalhaus (specifically Harriss's 1985 translation of "Die Musik des 18.Jahrhunderts"), Edward J. Dent, Otto Erich Deutsch, Leo Schrader, Theodor Strakova, and several others. Notes and annotated articles about various composers form the second sub-series of composer files. In addition to smaller files on Berio, Berwald, Fibich, Foerster, Gyrowetz, Janaček, Parry, Pfitzner, and Sonneleiter, are extensive files on C.P.E. Bach, Beethoven, Brahms, Caldera, Challis, Grove, Gassman, de Guera, Mahler, Mozart, Pleyel, Raff, and Wagenseil. The composer files are followed by the sub-series subject files. A sampling of topics represented in the subject files sub-series include 19th-century English symphony, Austrian organs, copyists, trumpet music, Viennese theatre calendars, and watermark tracings. The research series is brought to an end with the bibliographic card files sub-series. This sub-series consists of note cards of bibliographic entries, many of which also bear brief annotations. These card files were organized by Brown into several groupings, including composers, Italian instrumental music, Symphonic Repertoire, Haydn, keyboard music, symphonic works by composer, and orchestras and orchestration.