The development of a computer-based simulation for emergency response exercise training to facilitate trainees' learning activities and learning outcomes is proposed. Some limitations in using these simulations in emergency services include a focus on small-scaled individual task training and highly controlled environments designed to measure trainees' performance. These problems decrease the realism of the simulation which should represent more diverse, open-ended, counter-intuitive and unpredictable environmental conditions. These problems could reduce learning outcomes brought about by allowing open-ended discussions and team working. Virtual worlds provide a new methodological framework for conducting emergency response exercises. This paper describes a research agenda for the development of a virtual training exercise for emergency response. It has three objectives: firstly, it highlights the issues of validity of exercises for emergency events; secondly, it reviews possible virtual worlds which could be deployed as test bed environments and presents methodologies for their evaluation. Lastly, it suggests a future development of a virtual environment that may be used to support the emergency planning community by considering an existing similar project