An important measure of the effectiveness of environmental impact assessment (EIA) is the extent to which it achieves its goals for environmental protection and management. To deter-mine this requires an examination of environmental outcomes for projects that have undergone EIA. Four case studies from Western Australia are described During project appraisal, strong emphasis was placed on the need for ongoing monitoring and management programmes. The implementation of these programmes was found to be central to successful achievement of project and environmental performance objectives. The case studies demonstrate that a strong relationship exists between EIA and ongoing environmental management in Western Australia.