Series three includes correspondence between the National Association of the Deaf and national organizations, international organizations, schools, interoffice communications, and individuals from around the US. A very large portion of this series is dedicated to letters received and sent to persons in the United States concerned with matters of equality for the deaf that the NAD could possibly assist with. These letters are organized by the state from which they were received or sent to.

The deafness series is made up of documents that involve the research of deafness, the situations of the deaf from other countries, and new technology to assist the deaf with everyday living such as assistive listening devices and advancements in telecommunications. Information on how to best communicate and assist the deaf published for hospitals, the police, and other public services is an interesting part of the deafness series.