Diagnostic agents, the"who" of a diagnosis, may play several roles. Some are organizational support roles(e.g., OD champion, resource provider, nonclient monitor) performed by one or more managers or staff personnel. There are also usually several roles associated with the unit of diagnostic focus(e.g., clients, informants, and representatives of those affected). And there are the several diagnostic roles(e.g., for diagnosis planning, data collection, data analysis, data feedback, and dissemination of the diagnosis). Because diagnosis always involves more than one person, the quality of their relationships is important. Whether or not there are third parties(e.g., external consultants, internal staff), helping and trust are key considerations, not always easy to establish and maintain given the inevitable differences in power and status between diagnostic players.