Marine habitats worldwide are contaminated with man-made debris. Plastic items consistently represent the major categories of marine debris by material type on a global basis. Plastic debris is unsightly; it damages fisheries and tourism, kills and injures a wide range of marine life, has the capacity to transport potentially harmful chemicals and invasive species and can represent a threat to human health. This document focuses on plastic debris and examines its sources, identifies impacts on ecosystems and economies, and by considering the life-cycle of plastic products that become marine litter proposes a framework for responding to marine debris issues in general. The evidence presented on global occurrence, including accumulation in the areas beyond national jurisdiction, on persistence, and transboundary sources, movements and impacts on marine biodiversity and ecosystems compounded by emerging data on potential impacts and fate makes a strong case for considering marine debris as a global environmental problem.