This paper considers progress made in the protection of the marine environment during the last 40 years. We conclude that the prevailing sectoral approach to marine policy and management has limited effectiveness and is overdue for replacement by a comprehensive overall strategy for social development and environmental protection. Two categories of scientific challenge, relating to marine pollution prevention in its broadest sense, are identified using material derived from the papers in this volume. The first involves science directed towards improvements in the reliability of assessments and predictions for current practices and chemicals. The second comprises areas of fundamental science that are crucial to developing knowledge required for long-term protection of the marine environment.