This collection is divided into four subgroups: Montana State Prison Records (1881-1974); Board of State Prison Commissioners Records (1890-1962); State Board of Pardons Records (1890-1965); and the United States Penitentiary, Montana Territory Records (1864-1878).

The records of the Montana State Prison are divided into five series. The general correspondence (1891-1916) contains letters between Frank Conley and Thomas McTague and the governor, the clerk of the Board of Examiners, and two suppliers to the prison. The outgoing correspondence (1909-1921) of Conley and McTague pertains to inmates (paroles, pardons, behavior, time served, restoration to citizenship, escapes, work camps, sale of goods produced by prisoners, etc.), supplies, prison employment, penology, personal business of Conley and McTague, etc. The financial records (1893-1963) include cash books, general ledgers, journals, prisoner accounts with Deer Lodge and prison stores, voucher registers, etc. The bulk of the prisoner records (1881-1974) consists of prison description sheets which include each prisoners' vital statistics, and information about the crime committed, the sentence received, and a list of past crimes. The prisoner records also include lists of a conduct record; criminal charges against former Montana State Prison inmates; lists of prisoners received and discharged; a medical treatment record; lists of prisoners who were pardoned, paroled, and received suspended sentences, diminished sentences, and restoration of citizenship; and prison population statements.

The records of the State Board of Pardons include minutes (1880-1926), prisoner records (1892-1922), and miscellany (1963, 1965). The minutes are primarily approvals of paroles. The prisoner records are correspondence and documents relating to specific prisoners' pardons.

The records of the Board of State Prison Commissioners are divided into seven series. The general correspondence (1905-1929) consists of correspondence of the clerk of the Board. The hearings series (1957) consists of a transcript of a hearing concerning an investigation of conditions at the prison. The legal documents (1907, 1927) consist of an agreement for the purchase of cement and an easement granted to a railroad. The minutes (1890-1962) primarily concern the approval of paroles, the discharge of prisoners, the termination of sentences, return of prisoners for violation of parole, transfer of prisoners to the State Hospital for the Insane, etc. For some years (1910-1927,1949-1954) there is a separate run of minutes that deals exclusively with paroles. There is some discussion of procedures, investigations, etc. The prisoner records (1913-1955) consist of suspended sentence orders. The reports series (1960) consists of a report by the Prison Advisory Board concerning prison industries. The miscellany series (1959, undated) includes blank forms, procedural guidelines, and interviews with prisoners relating to the approval of "good time".

The Records of the United States Penitentiary, Montana Territory, are divided into six series. The general correspondence series (1875) consists of correspondence sent by W. F. Wheeler concerning housing prisoners. The incoming correspondence series (1874-1876) consists of correspondence received by W. F. Wheeler concerning housing prisoners and leasing space in court rooms. The financial records series (1886-1889) consists of an expense journal kept R. S. Kelley. The legal documents series consists of leases, memoranda of agreement and miscellany concerning housing prisoners, operating the prison and construction of the prison. The reports series (1873, undated) consists of reports of the Directors, the Physician, the Warden, and the U.S. Grand Jury. The miscellany series (1868-1878) consists of documents regarding the construction of the prison, inventories and rules and regulations. Restriction: Prisoner description sheets are restricted from public use due to their fragility. An archivist can search these sheets and provide the researcher with a receival date at the prison. This date will allow the researcher to find the prisoner description sheet on State Microfilm 36, where the description sheets are arranged by date received at the prison. Researchers are advised to provide the archivist with all possible variations of the prisoner's name.