A majority of treated sewage sludge (biosolids) from U.S. wastewater treatment plants is applied to farmland as a soil amendment. Residents living close to treated farmland have reported becoming ill following land application of sludge. No systematic tracking or investigation of these reports or of land application practices that could affect off-site migration of chemical and biological constituents of the sludge has occurred, however. In the study described in this article, the authors conducted a web-based survey and phone interviews with officials at federal, state, and local regulatory and health agencies and municipal wastewater treatment plants for input on how to design and implement an investigation protocol for tracking and responding to reports of human illness near land application sites. Officials expressed a need for and interest in implementing a systematic, standardized investigation protocol and offered insights on aids and barriers to its use and collaboration among diverse agencies. Additional opinions and innovative solutions expressed in this article will assist interested users in the implementation of the investigation protocol.