This paper reports on a study that was a response to a call from the UK government's Department of Children, Schools and Families for research into the link between the work of schools that address sustainability and the UK's national sustainable development indicators. This was part of the government's sustainable schools initiative, developed as a contribution to the UN's Decade of Education for Sustainable Development. The paper uses the four capitals model of Herman Daly and Donella Meadows to critically examine, firstly, how a school might make such a contribution to sustainable development, and, then, how we might come to know how effectively this is progressing. In doing this, the paper builds on Webster's work about the stages that a sustainable school might go through in its development, and the result is three sets of process descriptors to guide a school's thinking about what it might do. These are presented in the sense of an embryonic and sketchy map to the terrain, rather than as a set of instructions or a detailed plan to follow.