WHAT HAS CHANGED SINCE 1992 ? TWO DIFFERENCES ARE worth noting between this issue and our previous issue on sustainable cities six years ago. The first is the greater number of examples of innova-tive environmental action plans for cities - most of them linked to Agenda 21,the document agreed at the United Nations Earth Summit in Rio de Janeiro in 1992. A second difference between 1992 and today is the evidence of greater interest in the theme of sustainable cities among a broader group of people and institutions.