PURPOSE: Practice facilitators ("facilitators") can play an important role in supporting primary care practices in performing quality improvement (QI), but they need complete and accurate clinical performance data from practices' electronic health records (EHR) to help them set improvement priorities, guide clinical change, and monitor progress. Here, we describe the strategies facilitators use to help practices perform QI when complete or accurate performance data are not available. METHODS: Seven regional cooperatives enrolled approximately 1500 small-to-medium-sized primary care practices and 136 facilitators in EvidenceNOW, the Agency for Healthcare Research and Quality's initiative to improve cardiovascular preventive services. The national evaluation team analyzed qualitative data from online diaries, site visit field notes, and interviews to discover how facilitators worked with practices on EHR data challenges to obtain and use data for QI. RESULTS: We found facilitators faced practice-level EHR data challenges, such as a lack of clinical performance data, partial or incomplete clinical performance data, and inaccurate clinical performance data. We found that facilitators responded to these challenges, respectively, by using other data sources or tools to fill in for missing data, approximating performance reports and generating patient lists, and teaching practices how to document care and confirm performance measures. In addition, facilitators helped practices communicate with EHR vendors or health systems in requesting data they needed. Overall, facilitators tailored strategies to fit the individual practice and helped build data skills and trust. CONCLUSION: Facilitators can use a range of strategies to help practices perform data-driven QI when performance data are inaccurate, incomplete, or missing. Support is necessary to help practices, particularly those with EHR data challenges, build their capacity for conducting data-driven QI that is required of them for participating in practice transformation and performance-based payment programs. It is questionable how practices with data challenges will perform in programs without this kind of support.