Improving participation in preventive activities will require finding methods to encourage consumers to engage in and remain in such efforts. This review assesses the effects of economic incentives on consumers' preventive health behaviors. A study was classified as complex preventive health if a sustained behavior change was required of the consumer; if it could be accomplished directly (e.g., immunizations), it was considered simple. A systematic literature review identified 111 randomized controlled trials of which 47 (published between 1966 and 2002) met the criteria for review. The economic incentives worked 73% of the time (74% for simple, and 72% for complex). Rates varied by the goal of the incentive. Incentives that increased ability to purchase the preventive service worked better than more diffuse incentives, but the type matters less than the nature of the incentive. Economic incentives are effective in the short run for simple preventive care, and distinct, well-defined behavioral goals. Small incentives can produce finite changes, but it is not clear what size of incentive is needed to yield a major sustained effect.