Unhealthy behavior is a major cause of poor health outcomes and high health care costs. In this paper we describe an agenda for research to guide broader use of patient-targeted financial incentives, either in conjunction with provider-targeted financial incentives (pay-for-performance, or P4P) or in clinical contexts where provider-targeted approaches are unlikely to be effective. We discuss evidence of proven effectiveness and limitations of the existing evidence, reasons for underuse of these approaches, and options for achieving wider use. Patient-targeted incentives have great potential, and systematic testing will help determine how they can best be used to improve population health.