Impact of a quality improvement program on primary healthcare in Canada: a mixed-method evaluation.PURPOSE:  Rigorous comprehensive evaluations of primary healthcare (PHC) quality improvement (QI) initiatives are lacking. This article describes the evaluation of the Quality Improvement and Innovation Partnership Learning Collaborative (QIIP-LC), an Ontario-wide PHC QI program targeting type 2 diabetes management, colorectal cancer (CRC) screening, access to care, and team functioning. METHODS:  This article highlights the primary outcome results of an external retrospective, multi-measure, mixed-method evaluation of the QIIP-LC, including: (1) matched-control pre-post chart audit of diabetes management (A1c/foot exams) and rate of CRC screening; (2) post-only advanced access survey (third-next available appointment); and (3) post-only semi-structured interviews (team functioning). RESULTS:  Chart audit data was collected from 34 consenting physicians per group (of which 88% provided access data). Between-group differences were not statistically significant (A1c [p=0.10]; foot exams [p=0.45]; CRC screening [p=0.77]; advanced access [p=0.22]). Qualitative interview (n=42) themes highlighted the success of the program in helping build interdisciplinary team functioning and capacity. CONCLUSION:  The rigorous design and methodology of the QIIP-LC evaluation utilizing a control group is one of the most significant efforts thus far to demonstrate the impact of a QI program in PHC, with improvements over time in both QIIP and control groups offering a likely explanation for the lack of statistically significant primary outcomes. Team functioning was a key success, with team-based chronic care highlighted as pivotal for improved health outcomes. Policy makers should strive to endorse QI programs with proven success through rigorous evaluation to ensure evidence-based healthcare policy and funding.