Series consists of a drawer of catalogue cards with information concerning most MNI Fellows from between the institute's opening to the 1970s. Much of this information consists of mailing addresses which were compiled in the late 1970s and early 1980s, and is thus likely no longer accurate. Many of the cards are also accompanied by photographs of the particular Fellow.

This series contains varied materials created or kept by Helen Kermott Penfield. The series consists of letters, almost exclusively from Wilder, personal documents, diaries, and memorabilia, including an extensive family chronicle composed by Helen. The materials reflect above all Helen’s relationship with Wilder, but give a glimpse of her childhood and education, service in the war, life in England, social activities in Montreal, and travels with Wilder. This series is divided into four sub-series: diaries, correspondence, personal papers, and memorabilia.

Referred to in Dr. Segall's "The evolution of the record system" as "Correspondence 1932-", the series contains papers relating to groups and societies in addition to personal correspondence.

Series consists of notes produced by Dr. Penfield on books and articles he had read.

This series contains a group of calendars, or diaries, kept by Dr. Penfield's wife between 1947 and 1974.

Series consists of newspaper and magazine article clippings collected by Dr. Penfield.

Series A contains correspondence concerning a wide variety of medical topics. The majority of this correspondence concerns Dr. Cone and his association with the Presbyterian Hospital, McGill University, the Royal Victoria Hospital and the Montreal Neurological Institute. Correspondence relating to the development of improved neurological instruments is also included in this series. Also includes obituaries of Dr. Cone.

This series contains typed drafts and published sermons both written and delivered by Dr. Penfield, as well as published sermons by various Presbyterian/United Church ministers.

Identified as "Office Files" in the series descriptions found in Box 308, this series consists of chequing records, cheque stubs, federal and provincial taxation records, daily record books (professional charges), donation records, bank deposit records, and account statements of Dr. Segall's practice. Box 469 also contains personal tax records circa 1982.

This series contains material concerning the "Sussex", an English Channel passenger steamer on which Dr. Penfield was travelling in 1916 when it was hit by a German torpedo.