This article reports the findings of a demonstrator project to evaluate how effectively Immersive Virtual Worlds (IVWs) could support problem-based learning. The project designed, created and evaluated eight scenarios within "Second Life" (SL) for undergraduate courses in health care management and paramedic training. Evaluation was primarily qualitative, using illuminative evaluation which provided multiple perspectives through interviews, focus groups and questionnaires with designers, facilitators, learning technologists and students. Results showed that SL provided a rich, engaging environment which enhanced authenticity of the scenarios, though there were issues of access and usability. The article concludes by drawing together the lessons learned which will inform educators who seek to design and develop learning scenarios in this medium.