Coastal zones are boundary areas, places where environments, cultures, and economic sectors encounter each other, conflict, and interchange. From a wide variety of disciplinary starting points, the contributions to this volume engage with boundary issues of key importance for the coastal zone. They are united in this effort by two guiding themes. First, they recognise that the problems of the coastal zone are together best seen as a development challenge rather than as a management challenge. Second, the challenge of the coasts requires a transdisciplinary response from the social and natural sciences. The contributions to Challenging Coasts address these themes through a diverse range of topics in a variety of coastal settings. Papers examine case studies in the South Pacific, Southeast Asia, West Africa, Europe, and Latin America. Subjects of focus include coastal zone development, biodiversity protection, marine park management, the threat of political-economic change to livelihoods, multiple-use conflicts, and the legal-institutional challenges of habitat protection. The volume as a whole is tied together in a first paper on boundaries and transdisciplinarity in coastal zone development. Challenging Coasts will be an important resource for students, researchers, teachers, and policy makers working on issues related to coasts and coastal zone development.