Following the onset of hostilities during World War I, non-naturalized “Enemy Aliens” by definition, were required to register with United States authorities as a national security measure. Under the provisions of a Presidential Proclamation of April 6, 1917, non-naturalized female aliens were likewise registered as an additional national security measure that included those women of American birth that were married to enemy aliens. Registrants include school children, divinity students, former United States soldiers and sailors, Roman Catholic nuns, the elderly and the infirm. For the State of Kansas the registered aliens represent a broad cross-section of the German-born population of the State.

The series contains original affidavits of registration that record personal information about each registrant, their photograph affixed to the majority of documents, and the registrants fingerprints. All of these are specific to Kansas, and more than half have the actual documents attached.