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 National Indian Gaming Commission (NIGC) subject files date from 1988 to 2005 and include materials produced by and about NIGC and the organization's efforts to support Native American economic development through gaming on Native American lands. Materials include reports, legislative documents, congressional records, testimonies, newsletters, publications, pamphlets, correspondence, memos, press releases, agendas, booklets, and newspaper articles.

The sociocultural subject files contain materials collected by Dr. Spilde about sociocultural issues related to Native Americans, Native American gaming, and gaming in the United States. Materials date from 1980 to 2007, with the bulk of materials dating from 1994 to 2005. Materials include socioeconomic impact studies and reports; annual reports; periodicals; memos; correspondence; notes; video recordings of televised programs; conference materials; promotional materials; booklets, pamphlets, and packets; journal articles; law review articles and legal briefs; and newspaper articles. The materials concern a variety of topics such as compulsive gambling, Native American health, environmental policy, the social cost of casino gaming, criminal activities, card counting, Native American culture, and the social impacts of gaming in the United States.

The socioeconomic subject files (1993-2003) contain materials collected by Dr. Spilde about bankruptcy and the socioeconomic impact of Native American gaming enterprises in the United. Materials include impact studies, reports, memos, press releases, informational materials, journal articles, legal briefs, and newspaper articles.