Series 1 primarily pertains to the land and water rights of specific American Indian tribes or peoples. Most of the communities represented by Byler are native to the Southwest, especially Arizona, though issues related to tribes and peoples residing in Washington state, the Midwest, and the Southeast are also documented.

Series 2 is composed of publications, drafts of legislation, memoranda, correspondence, court documents, and other materials related to issues impacting multiple tribes or the Native American community as a whole. Topics documented include land claims, water rights (especially as they pertain to the Central Arizona Project), mining, child welfare, religious freedom, education, tribal governance, and social services (the latter three issues particularly as they pertain to Public Law 93-638, the Indian Self-Determination and Education Assistance Act).

Series 3 contains administrative materials from Gerard, Byler and Associates and William Byler Associates, including the firms' financial statements, contracts between Byler's firms and his American Indian tribal clients, and invoices sent to the tribes for Byler's legal services.

Series 4 is composed of papers from legislative campaigns that were generated by consultant Fraser Barron and collected by William Byler, including notes, correspondence, government documents, and reports. The papers mostly pertain to the Havasupai tribe's claims to territory in the Grand Canyon and the water rights of other Arizona tribes.