Much of the correspondence is in the form of letters received and sent. Letters received are arranged according to author of the letter, with each author separated into a folder. Of the six folders of correspondence sent by Lemonnier, only two contain original letters. The other four folders contain transcripts of letters Lemonnier sent to his family in France between 1859 and 1874. The originals of these transcriptions are kept in the Archives de la Roche in France and were sent to Notre Dame by Henri Lemonnier-Dubourg between 1938 and 1940. Included with these transcriptions is a genealogy of the Lemonnier family. All of these transcriptions, as well as much of the correspondence, are in French.

This series contains the diaries, sermons, notebooks, essays, and other personal documents generated during 1845-1874. The diaries cover the years 1864-1870 and are arranged chronologically. The sermons are also arranged chronologically, where dates are known, and cover roughly the period of Lemonnier's stay at Notre Dame (1861-1874). Although the notebooks, essays, scripts of plays and notes cover Lemonnier's stay at Notre Dame, they are more reflective of his seminary education (1857-1861). Much of this material from this period is in French. Some of the personal documents were generated during his residence at Notre Dame. Included among these are certificates, railroad passes, tickets; faculties for scapulars, and permissions granted to students as Prefect of Discipline (1863-1865).

This series contains three folders of material collected on Lemonnier. Included in this series is a scrapbook detailing Lemonnier's life (1874); a manuscript of a eulogy on Lemonnier(possibly by Fr. Corby); a mass card and lock of hair; and a poem written in tribute to Lemonnier (1879).