The case study method supported by interviews is used widely by IS researchers. In ‘messy’ problems, such as the adoption of e-procurement across manufacturing supply chains, a more collaborative approach is needed to explore and make sense of the problem domain. This paper proposes the use of qualitative politicised influence diagrams - QPID – to enable the investigator to structure the process of collaborative investigation as part of an action case strategy. The paper describes how QPID workshops are used as part of a multiple methods research design to support and help practitioners articulate the issues surrounding the adoption of e-procurement in the automotive industry. Four outcomes of the approach are identified: 1) QPID is a systems modelling method that is meaningful to practitioners, 2) QPID can be used to promote good quality conversations, 3) QPID models provide a consistent notation for case description that supports cross-case and industry level analysis, and 4) collaborative workshops, through the creation of trust and shared understanding between researcher and practitioner, can provide a platform for subsequent interventions.