Introducing the SUE-MoT (metrics, models and toolkits for whole-life sustainable urban development) series, this paper highlights some of the barriers that need to be addressed if the vision for holistic assessment is to be realised. The complexities of sustainability assessment raised in this paper will be further discussed in detail in the SUE-MoT series of papers that will be published in forthcoming issues of this journal. This paper highlights the priorities to address when assessment tools are presented to decision makers of urban development projects. This discussion is limited to the issues, values and solutions in the UK context