Variable success with quality improvement (QI) efforts in ambulatory care is often attributed to differences in local contexts. Identifying and addressing patient-, practice-, or community-level contextual factors might improve implementation of QI projects. The authors developed and validated a framework for a Practice Context Assessment (PCA), and then created the PCA instrument to glean insights from staff on contextual factors and distributed it at 10 ambulatory practice sites. The PCA framework showed acceptable expert-assessed content validity, with content validity index scores ranging from 0.74 (community engagement) to 0.97 (leadership). The PCA instrument comprised several scales grouped into 7 domains with Cronbach α scores from 0.83 (leadership) to 0.95 (patient and family engagement). The PCA framework provides a valid construct to help ambulatory practices understand contextual issues that might influence QI projects. A revised version of the PCA instrument is now ready for further testing.