Subseries consists of subject files of correspondence (C/S = Correspondence/Subject). Most of these files were active up until Dr. Penfield's death and are largely grouped by subject. They may extend over a number of years but seem to indicate a continuing interest on the part of Dr. Penfield.

Sub-series consists of general correspondence, essentially inactive files kept for reference (C/G = Correspondence General).

Sub-series includes all of Dr. Penfield's "correspondence-domestic", or personal correspondence, which was taken from his office at the Montreal Neurological Institute. This sub-series includes material which Dr. Penfield had collected before arriving at McGill in 1928. In particular, it includes correspondence between Dr. Penfield and his wife, Helen Kermott Penfield.

This sub-series includes the notes, drafts, and correspondence Dr. Penfield created and collected in producing his various non-book writings. (W/P = Writings / Published)

This sub-series includes the notes, drafts, correspondence, and other records Dr. Penfield produced and collected in creating his various books. (W/B = Writings / Books)

Subseries consists of correspondence, paperwork, and articles concerning films, recordings, and television broadcasts that involved Dr. Penfield.