This book presents the results of the five year Butterflies for the New Millennium project organised by Butterfly Conservation, the Centre for Ecology and Hydrology and the Dublin Field Naturalists' Club in 1995-99. However, it is much more than just an Atlas - as well as maps showing distribution and changes of distribution, there is information on flight periods, abundance, population level, ecology and conservation - all presented in a clear, attractive and accurate style. There is also a wealth of background information, putting the survey in context and explaining its methodology, as well as discussing the results and their implications. While 15 species have shown evidence of recent range expansion, some quite dramatic, more worrying is the fact that no less than 29 species (half the British total) have shown signs of range loss in the last two decades. Most of these species are habitat specialists, something that makes their conservation more difficult. However, this book goes a long way towards providing the baseline information and, hopefully, raising the public awareness which are both necessary to start improving the current situation. Overall, organisers, authors, publishers and everyone else involved in the publication of this book deserve every credit. The publishers claim this is a book for everyone with an interest in butterflies, 'from amateur to naturalists to professional conservationist and policy-makers' and they are right. If you are interested in butterflies in any way you must have this book. It is the best book on British butterflies ever published. If it inspires people to take up an interest in butterflies and encourages conservationists and planners to carry out he conservation measures suggested, it could also be the most important.