RAND Europe has conducted a cost-effectiveness analysis of a portal on drug misuse prevention. The study starts with a review of the effectiveness of information provision via the Internet and of the effectiveness and cost-effectiveness of drug misuse prevention in general. The authors discuss and calculate what the effect of a portal may be, such as increased practitioner effectiveness and decreased communication costs. They then calculate the direct costs and possible benefits of the portal under three scenarios: low, medium and high growth in the number of prevention practitioners reached. The main result is that the benefits of the portal will soon outweigh the costs if medium or high growth in the number of practitioners reached happens, but that the balance will be less positive in case of low growth. In any of the scenarios, the societal and other indirect benefits of improved prevention practice in the short and long terms cannot be calculated. This implies that the portal is probably useful and effective, and mostly cost-effective.