Sustainable development, 20 years on: methodological innovations, practices and open issues

The aim of this introductory paper is to put into perspective some key methodological and practical issues raised by the analysis and implementation of Sustainable Development (SD) approaches in recent years. The key point made here is that, while SD analysis has gained in depth and methodological improvement, implementation issues remain problematic as they underlie serious institutional and strategic constraints. Through different angles, the five papers gathered in this special issue provide several illustrations of this ambivalence and emphasise some key practical challenges facing the design of workable SD policies and measures.