To improve health and reduce health inequalities, public policymakers need to find the best solutions to the most burdensome health problems, the best ways to fit these solutions into complex and often overstretched and underresourced health systems, and the best ways to bring about the desired changes in health systems. Systematic reviews can inform public policymaking by providing research-based answers to these questions. Public policymakers can encourage more informed policymaking by asking to see systematic reviews on priority issues, commissioning reviews when none exists, and placing more value on such work in their deliberations and in their interactions with stakeholders. Donors and international agencies can encourage more informed public policymaking by supporting national and regional efforts to undertake reviews and assess their local applicability, and by supporting regional or worldwide efforts to coordinate review and assessment processes.