Background: Shared decision making (SDM) in breast cancer care improves outcomes, but it is not routinely implemented. Results from the What Matters Most trial demonstrated that early-stage breast cancer surgery conversation aids, when used by surgeons after brief training, improved SDM and patient-reported outcomes. Trial surgeons and patients both encouraged using the conversation aids in routine care. We will develop and evaluate an online learning collaborative, called the SHared decision making Adoption Implementation Resource (SHAIR) Collaborative, to promote early-stage breast cancer surgery SDM by implementing the conversation aids into routine preoperative care. Learning collaboratives are known to be effective for quality improvement in clinical care, but no breast cancer learning collaborative currently exists. Our specific aims are to (1) provide the SHAIR Collaborative resources to clinical sites to use with eligible patients, (2) examine the relationship between the use of the SHAIR Collaborative resources and patient reach, and (3) promote the emergence of a sustained learning collaborative in this clinical field, building on a partnership with the American Society of Breast Surgeons (ASBrS). Methods: We will conduct a two-phased implementation project: phase 1 pilot at five sites and phase 2 scale up at up to an additional 32 clinical sites across North America. The SHAIR Collaborative online platform will offer free access to conversation aids, training videos, electronic health record and patient portal integration guidance, a feedback dashboard, webinars, support center, and forum. We will use RE-AIM for data collection and evaluation. Our primary outcome is patient reach. Secondary data will include (1) patient-reported data from an optional, anonymous online survey, (2) number of active sites and interviews with site champions, (3) Normalization MeAsure Development questionnaire data from phase 1 sites, adaptations data utilizing the Framework for Reporting Adaptations and Modifications-Extended/-Implementation Strategies, and tracking implementation facilitating factors, and (4) progress on sustainability strategy and plans with ASBrS. Discussion: The SHAIR Collaborative will reach early-stage breast cancer patients across North America, evaluate patient-reported outcomes, engage up to 37 active sites, and potentially inform engagement factors affecting implementation success and may be sustained by ASBrS.