A Design for Service (DfS) approach has been linked with impacts that significantly alter touchpoints, services and organisational culture. However, there is no model with which to assess the extent to which these impacts can be considered transformational. In the absence of such a model, the authors have reviewed literature on subjects including the transformational potential of design; characteristics of transformational design; transformational change; and organisational change. From this review, six indicators of transformational change in design projects have been identified: evidence of non-traditional transformative design objects; evidence of a new perspective; evidence of a community of advocates; evidence of design capability; evidence of new power dynamics; and evidence of new organisational standards. These indicators, along with an assessment scale, have been used to succesfully review the findings from a doctoral study exploring the impact of the DfS approach in Voluntary Community Sector (VCS) organisations. This paper presents this model as a first-step to establishing a method to helpfully gauge the extent of transformational impact in design projects.