The Nellie Morrill Diary contains personal notes on day to day activities, and sections for monitary and memoranda accounting. The diary is primarily composed of descriptions of the Morrill's daily activities, including weather, responsibilities, meals, recreational activities, and brief accounts of meetings. Her entries often feature references to "Henry" (Henry Waldo), to whom she became engaged in March of 1865 and who she later married. Although kept in the final part of the Civil War, there are very few references to war-time news or events, though she notes on Sunday, April 23, "Went to meeting Abe Lincolns [sic] funeral sermon was preached in the afternoon..."

Morrill sometimes slips into an apparent code, replacing letters within names with numbers, but it is done inconsistently.