The scientific rigor of education research has improved dramatically since the year 2000. Much of the credit for this improvement is deserved by Institute of Education Sciences (IES) policies that helped create a demand for rigorous research; increased human capital capacity to carry out such work; provided funding for the work itself; and collected, evaluated, and made available the results of that work through the What Works Clearinghouse. Major challenges still remain for education research, however. One challenge is dealing with the replication crisis that has plagued other scientific fields and is likely to be a problem in education science. A second challenge is better supporting the generalizability of education research. A third challenge is adapting our rigorous research designs to the increasing complexity of our interventions and our questions about the mechanisms by which these interventions achieve their effects. Promising approaches to meet each of these challenges are suggested.