Recent outbreaks of disease in domestic animals, humans and wildlife illustrate the relative importance of infectious diseases and the vulnerability of susceptible animals. Why do such diseases emerge? What are the factors that lead to dramatic epidemics? How can we apply our knowledge to improve the methods of control? These are just some of the questions addressed in this book, which seeks to develop and apply an ecological approach to an understanding of epidemiology in wild animal populations. The development of mathematical models in the dynamics of infectious diseases is a field that has seen rapid growth over the last decade. There is now a need to challenge these models with the data and to bring vets and field workers closer to the disease issues. This book was conceived to identify the exciting questions and set the future research agenda. 50 of the most active workers met in Trento, northern Italy, to brainstorm the issues, and from this the editors have moulded a synthesis that captures the excitement and importance of this expanding field.