The National Congress of American Indians (NCAI) subject files date from 1997 to 2011 and include materials produced by and about NCAI and the organization’s efforts to represent the interests of Native American governments and communities. Materials include reports, legislative documents, newsletters, publications, pamphlets, memos, press releases, agendas, informational booklets, and newspaper articles. The majority of the subseries focuses on joint NCAI and National Conference of State Legislatures (NCSL) projects about health, renewable energy, government-to-government relationships, and Native American sovereignty.

Additional materials relating to NCAI can be found in the National Indian Gaming Association (NIGA) and the National Congress of American Indians (NCAI) Joint Task Force files and the National Congress of American Indians (NCAI) and Bureau of Indian Affairs (BIA) Data Management, Needs Assessment, and Auditing Workgroup files. Materials directly related to Spilde’s activities as a member of the task force and workgroup were placed in those subseries. Other materials about NCAI were placed in the NCAI subject files.

The Sin of Harold Diddlebock sub-series (1944-1951) contains materials related to the development, production, and post-production of the California Pictures Corporation film, The Sin of Harold Diddlebock (1947), also known as Mad Wednesday. Records include advertising and publicity, legal, production and direction, and story development records, as well as film soundtracks. Materials included are correspondence, pressbooks, newspaper and magazine clippings, black-and-white photographic prints and negatives, music scores and sheets, contracts, agreements, screenplays, continuities, and casting sheets.