This series contains correspondence, meeting minutes, newsletters, notes, brochures, and other ephemera from the many professional and social organizations William Pahlmann belonged to. The materials in this series regard Pahlmann's membership in a number of different organizations, including country clubs, social clubs, arts advisory councils, and organizations relating to architecture and interior design. The Memberships Series does not include materials from the American Institute of Interior Designers (AID); these items are located in Series 5, AID Files.

Two folders in this series specifically concern Pahlmann's interactions with the Parson's School of Design. These materials cover Pahlmann's participation in the school's fundraising efforts, his appearances as a guest lecturer, and his opinions of the school during the 1950s and 1960s.

Items in this series highlight Pahlmann's professional activities and his extensive social networks. These materials also help illustrate many of Pahlmann's personal opinions and activities outside of the interior design profession. They also correspond to many of the materials found in the Publicity Series and the Publicity Books Series.