THRESHOLDS seeks to contribute to the development of Sustainability Science and through the implementation of a procedure for policy formulation based on the development of a target setting process that integrates scientific knowledge on thresholds of indicators of environmental sustainability, the socio-economic activities that impinge in these indicators and the components of their vulnerability, and the evaluation of the resulting externalities associated with these socioeconomic activities. THRESHOLDS carries out innovative crosscutting research to develop, improve and integrate tools and methods to provide the basis to formulate sustainable strategies through research to deliver the scientific tools to identify Thresholds and Points of No-return of Environmental Sustainability and externality valuations required to define targets for the development of the European Sustainable Development Strategy. The THRESHOLDS IP will confront complex behaviour of ecosystems, such as regime shifts between alternative stable states, and complexity in valuation of the sectors affecting environmental quality, such as non-linear cost-pressure relationships and multi-sectorial situations to develop procedures that accommodate to the complexity of the socio-economic and environmental systems. The tools developed will be applied to case studies in the European coastal zone, where policy needs are pressing, involving increasing levels of complexity, from local to pan-European. THRESHOLDS IP will draw on the extensive data sets and research results produced on the basis of national efforts as well as previous framework programmes, which have focussed on major environmental problems and have delivered models and data which can be used to define Thresholds and Points of No Return. The THRESHOLDS IP, will, therefore, build on the European Research Area concept and add value to the applications of results derived from national and FP 6-funded research.