Although value-based purchasing (VBP) holds promise for encouraging quality improvement and addressing rising costs, currently there is limited evidence about how best to structure and implement VBP programs. In this commentary, we highlight several issues for improving evaluations of VBP programs. Implementation research can be enhanced through early and continuous assessment and greater variation in program designs. Impact research can be improved by creating better outcome measures, increasing the availability of linked patient-level data, and advancing synthesis research. We offer several recommendations for improving the foundation to conduct evaluations of VBP programs to better inform policy and practice.