The interviews, interview transcripts, documentary and related material are included in various formats listed in the contents section.

Peter Wege and Earl and Donnalea Holton were researched but not ultimately interviewed due to conflicts with their schedules. For archival purposes, the Council of Michigan Foundations provided the SOUL project with a DVD of Wege relevant to his receiving the Mawby Award in 2006. The interview with Fred Keller, done late in the project, was captured strictly on audiotape. Former city historian, Gordon Olson; Grand Rapids Community Foundation president, Diana Sieger; Calvin College professor of history, James Bratt; and Grand Valley State University professor of philanthropy, Joel Orosz are also featured on the documentary but their remarks were scripted rather than edited from fuller interviews.