This series contains internal administrative and financial records for the Seneca Club of Kings County. Financial records include leases and a mortgage for the Club headquarters at 93 Division Ave, tax documents, cash books, and expense ledgers. Administrative records include membership ledgers, Executive Committee meeting minutes and correspondence, and certificates and proclamations. Also included are ledgers from the War Effort and Entertainment committees.

The majority of material in this series is comprised of correspondence from local residents to elected officials and Seneca Club representatives regarding local and personal matters. Elected officials often referred constituent correspondence to the Seneca Club, and conversely the Seneca Club lobbied elected representatives on behalf of neighborhood residents. There is a significant body of correspondence regarding employment opportunities, immigration status, and military service, including deferements and reassignments of active duty soldiers during the Vietnam War. There is also a significant group of correspondence with the New York City Housing Authority (NYCHA) regarding the availability of apartments in new NYCHA developments. Other topics represented in constituent correspondence include crime and incarceration, federal benefits, education, and local development issues in Williamsburg and Greenpoint. The series also includes correspondence from Seneca Club leaders, and a small number of subject files.

Souvenir programs and other ephemera from the Seneca Club's annual Dinner-Dance comprise the majority of this series, with the bulk of programs dating from the Diamond Jubilee dinner in 1973 until the present. A number of earlier Seneca Club events are also represented in this series, as well as several programs from the Brooklyn Democrats Awards Dinner.

This series contains electoral campaign materials, including ephemera produced by candidates, as well as materials produced by the Sencea Club itself. Candidates that are particularly well-represented in this series include Abe Beame, Al Lownstein, George Swetnick, and Steve Cohn. This series also includes one ledger containing handwritten and published election results, clippings, and campaign advertisements from 1928 through 1966 concerning races for a variety of national, state, and local positions. Other materials included in the ledger are election appeals sent out by the Club with voting guidance, poll information, and candidate photographs with a suggestion to take these recommendations into the voting booth. The series also includes a sample voting machine.

This series includes photographs of Seneca Club events and members, as well as photographs of affiliated organizations and prominent politicians. There are a number of unidentified photographs in this series. This series also contains six plaques presented to Seneca Club members.

Membership cards were maintained at the Seneca Club offices, and were used by the organization's leadership to track members and their interactions with the Seneca Club. Membership cards include names, addresses, and dates and descritpions of individual assistance provided by the Seneca Club. The Seneca Club frequently provided neighborhood residents with assistance in housing, employment, immigration, military status, and more. This information was used to encourage voter turnout during election campaigns.