To evaluate the impact of a statewide intervention to implement evidence-based measures on breast re-excision rates, researchers will use benchmarked performance reports based on existing discharge data. Several types of hospitals offer breast-conserving surgery (BCS), a typical procedure for treating breast cancer. Since studies have shown varying rates of re-excision after BCS, this variable has been highlighted as a valuable area for advancement. Re-excision rates 60 days after breast cancer surgery using breast cancer BCS were compared using Wisconsin Hospital Association discharge data (2017-2019). Using a logistic mixed-effects model with repeated measures and controlling for age, payer, hospital volume, and hospitals as random effects, the analysis estimated the difference in the average change pre- and post-intervention between Surgical Collaborative of Wisconsin (SCW) and nonparticipating hospitals. During the intervention’s 5 sessions spread out between 2018 and 2019, surgeon champions discussed new guidelines, successes, and failures in implementing those guidelines and planned the next steps for moving forward. Reports on performance against industry standards were provided in confidence. There were 3,692 SCW breast surgeries and 1,279 nonparticipating hospital procedures in 2017; re-excision rates varied from 5% to more than 50% between institutions. At the outset, there was not a statistically significant difference in the re-excision rates between SCW and nonparticipating hospitals (16.1% vs. 17.1%, P=0.47). While the rate of re-excision fell dramatically for SCW, it did not for non-participating hospitals (odds ratio=0.69, 95% CI=0.52-0.91). Increased quality and lower costs could result from fewer re-excisions after BCS implementation, as can benchmark performance reporting and collaborative quality improvement. This research proves that administrative data can serve as a solid foundation for quality partnerships statewide. Using previously collected information reduces costs and introduces a novel perspective that can be applied in various clinical settings to increase patient involvement.