This article proposes an alternative approach in sustainability assessment. The conceptual framework was developed by modifying Ken Wilber's All Quadrants, All Levels (AQAL) approach, and focuses on the inter-relatedness/inter-connection of various perspectives inherent to the concept of sustainability. To look at how our framework can facilitate the practice of sustainability assessment, we apply the framework to examine the relationships between social systems and the environmental changes in the Ili River basin across the period 1900?2008. This approach enables us to investigate (...) the environmental problems of the Ili River basin in a four-quadrant framework, and combine the empirics of quadrants obtained from traditional disciplinary methodologies. The four-quadrant framework adopted in this study illustrates the interlocking relationships among various perspectives of environmental issues in the Ili River basin, namely, physical perspective, personal perspective, cultural perspective, and social perspective. In particular, the protruding development (evolution) of the lower right dimension is the fundamental cause of the environmental degradation and its related social problems in the Ili River basin. Compared to other established approaches in literature that emphasize on the tradeoffs of various perspectives of sustainability, our findings indicate the potential contributions of four-quadrant framework to sustainability assessment through its focus on the inter-relatedness/inter-connection of different perspectives. (shrink)