Social impact assessment (SIA) presents an important opportunity to draw cross-cultural encounters arising from project-based development efforts into wider procedures of engagement and negotiation that might address the imbalance in relationships between local communities, project proponents and states. In the SIA literature, however, ethical considerations have received relatively little explicit attention, with greater attention given to outcomes in the form of negotiated agreements and financial and employment results. This paper considers the question of SIA methods from the standpoint of recent Australian national guidelines on ethical engagement with Australian Indigenous people, and argues for much greater attention being given to process and its implications for just and sustainable outcomes in SIA research.In thinking about the practices of cross-cultural engagement, whether it is in the form of personal encounters with cultural difference, formal processes of intercultural consultation in professional fields such as planning and service provision or structured settings such as cross-cultural negotiation and social assessment, we are often confronted with circumstances that are somewhat distant from social theory's complex abstractions of relationships between abstract selves and abstract others. Concern with difference and alterity has really driven much of Western philosophy for more than 50 years, producing some of the most exciting and frustrating debates in social science. Yet it is the performance rather than theorising of cross-cultural engagements that constitutes and reconstitutes societies and the social and environmental relationships within and between them. It is also the performance of these engagements that challenges societal assumptions of how things are, can be and should be.The field of social impact assessment (SIA) is one in which cross-cultural relationships, or at least the interface between co-existing cultural groups in the context of a development project, is subject to some degree of critical scrutiny