The workshop will introduce participants to the recently proposed IUCN Red List Categories and Criteria for Ecosystems (Rodríguez et al., 2011, Conservation Biology 25: 21-29), inviting them to bring their own datasets and test them against the quantitative thresholds. By the end of the workshop, they will have either generated categories for their case study or tested a dataset provided to participants with no data of their own. With these tools in hand they will be able to replicate the exercise in their place of work or study, and expose others to the proposed categories and criteria. Participants will be invited to join a working group sponsored by the Commission on Ecosystem Management of IUCN (http://www.iucn.org/about/union/commissions/cem/cem_work/tg_red_list/), to facilitate future exchange and experience-sharing among them, their colleagues or anyone interested. We expect this session to be part of the launching platform of a global effort to systematize ecosystem risk assessment and conservation priority setting, and for building a freely available on-line portfolio of case studies and their underlying data.