The authors review the influence of state, national and international large-scale assessments (LSAs) on education policy and research. They distinguish between two main uses of LSAs: as a means for conducting research that informs educational reform and LSAs as a tool for implementing standards and enforcing accountability. The authors discuss the influence of the international TIMSS study on US mathematics standards and the development of the Common Core as an example of LSA's potential for research-based reform. They also examine how the controversy over using assessments to evaluate teacher performance suggests some of the problems with using LSAs as a lever for policy. They conclude by suggesting that the "assessment to inform policy" model may be more promising (and yield greater long-term fruits) than an "assessment as policy" model.