The view is widely held that proactive integrated management of coastal zones is a rewarding strategy in the long run. It appears, however, rather difficult to substantiate this claim, both theoretically and empirically. Theoretically, first of all because the concepts of 'proactive' and 'integrated' still await their proper definitions and second, because the role of seemingly important variables and their interactions is not well understood, including the discount rate, the process of technological development and decision making under uncertainty. In addition, extensive empirical information is needed on the positive and negative external effects, their costs and benefits in time, as well as tile investments and operational costs of coastal zone management strategies, whether integrated or not Resolving these issues is beyond the scope of this paper, which merely attempts to highlight some of the relevant aspects and to provide some theoretical argumentation and conditions in favour of proactive integrated coastal zone management. This argumentation concerns external effects, economics of scale, the discount rate, the precautionary principle and the question 'learn or act?' with regard to decision making under uncertainty.