Definitions of and judgments regarding effectiveness in social impact assessment (SIA) depend on how the purposes of SIA are understood. They are defined differently by various interests that participate in, or are affected by, impact assessment processes, and the concept of 'effectiveness'
and the issue of what is required to achieve it are both contested and contextual. This article reviews a number of different approaches to SIA and outlines what effectiveness might mean for each. It then considers, at two levels, what 'effective SIA' involves in the context of large-scale
resource development on Aboriginal land in Australia. The first level involves control of SIA. For indigenous peoples who have historically been excluded from and ignored by SIAs undertaken as part of government approval processes, Aboriginal control is an essential prerequisite for 'effective
SIA'. However, control only creates the potential for effectiveness. The second level of analysis involves the practical activities that must be undertaken, and issues that must be addressed, to realize this potential. The author develops a matrix designed to help identify and manage these
activities and issues in a systematic way.