Series III. Katherine May Crowninshield (1844-1892) Papers consist of three subseries. Subseries A. Financial Records contain several account books and cancelled checks.

Subseries B. Correspondence includes letters written to Crowninshield by her husband and her children. There are a few letters from Benjamin Williams Crowninshield before they were married, and one in particular speaks to Benjamin Williams's desire to be married. Most of the letters from the children are from Francis Boardman Crowninshield (1869-1958) and Bowdoin Bradlee Crowninshield (b. 1867). The letters from Francis Boardman are written while he was at boarding school. The letters to Benjamin Williams from Katherine Crowninshield contain mostly daily household events.

Subseries C. Personal Papers contains one folder, consisting of Katherine May Crowninshield's last will and testament, as well as dance cards from 1865.