Marine protected areas (MPAs) have an important role in marine conserva­ tion programmes around the world. Although most have been established relatively recently when compared with protected areas on land, there is considerable expertise on their identification, setting up and management. Some techniques have been adapted from those used on land. Others are novel, and unique to marine conservation. The chapters in this book give an insight into this fast developing field where experiment and innovation work alongside techniques which have been tried and tested. The guiding princi­ ples behind key stages in the setting up and management of MP As are described, and case studies illustrate how they have worked. While it is most encouraging to read about the successes, the case studies also point to difficulties which have been encountered. Not all of the examples are new or recent but, together, they illustrate what is happening in this field.